diff --git a/.gitignore b/.gitignore
index 3d901ba..33f789d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,12 +2,20 @@
 venv/
 app/__init__.py
 app/__pycache__/
+.DS_Store
+app/.DS_Store
 app/sqlite_commands.py
 app/static/usr/*.jpg
 app/static/img/
 app/static/frequency/frequency_*.pickle
 app/static/frequency/frequency.p
-app/static/wordfreqapp.db
+app/wordfreqapp.db
+app/db/wordfreqapp.db
 app/static/donate-the-author.jpg
 app/static/donate-the-author-hidden.jpg
-app/model/__pycache__/
\ No newline at end of file
+app/model/__pycache__/
+app/test/__pycache__/
+app/test/.pytest_cache/
+app/test/pytest_report.html
+app/test/assets
+app/log.txt
diff --git a/Dockerfile b/Dockerfile
index 284195a..55e5946 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,5 @@
-FROM tiangolo/uwsgi-nginx-flask:python3.6
-COPY requirements.txt /app
-RUN pip3 install -r requirements.txt -i https://mirrors.aliyun.com/pypi/simple/
-COPY ./app /app
+FROM tiangolo/uwsgi-nginx-flask:python3.8-alpine
+COPY requirements.txt /tmp
+COPY ./app/ /app/
+RUN pip3 install -U pip -i https://mirrors.aliyun.com/pypi/simple/
+RUN pip3 install -r /tmp/requirements.txt -i https://mirrors.aliyun.com/pypi/simple/
diff --git a/Jenkinsfile b/Jenkinsfile
index 2633859..c3772cc 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -10,8 +10,8 @@ pipeline {
     stages {
         stage('MakeDatabasefile') {
 	    steps {
-	        sh 'touch ./app/static/wordfreqapp.db && rm -f ./app/static/wordfreqapp.db' 
-	        sh 'cat ./app/static/wordfreqapp.sql | sqlite3 ./app/static/wordfreqapp.db'
+	        sh 'touch ./app/wordfreqapp.db && rm -f ./app/wordfreqapp.db' 
+	        sh 'cat ./app/static/wordfreqapp.sql | sqlite3 ./app/wordfreqapp.db'
 	    }
 	}
         stage('BuildIt') {
diff --git a/README.md b/README.md
index 14cc9aa..15fc966 100644
--- a/README.md
+++ b/README.md
@@ -61,15 +61,15 @@ My steps for deploying English on a Ubuntu server.
 
 
 All articles are stored in the `article` table in a SQLite file called
-`app/static/wordfreqapp.db`.
+`app/db/wordfreqapp.db`.
 
 ### Adding new articles
 
-To add articles, open and edit `app/static/wordfreqapp.db` using DB Browser for SQLite (https://sqlitebrowser.org).
+To add articles, open and edit `app/db/wordfreqapp.db` using DB Browser for SQLite (https://sqlitebrowser.org).
 
 ### Extending an account's expiry date
 
-By default, an account's expiry is 30 days after first sign-up.  To extend account's expiry date, open and edit `user` table in `app/static/wordfreqapp.db`.  Simply update field `expiry_date`.
+By default, an account's expiry is 30 days after first sign-up.  To extend account's expiry date, open and edit `user` table in `app/db/wordfreqapp.db`.  Simply update field `expiry_date`.
 
 ### Exporting the database
 
@@ -95,7 +95,7 @@ sqlite3 wordfreqapp.db`.  Delete wordfreqapp.db first if it exists.
 ### Uploading wordfreqapp.db to the server
 
 
-`pscp wordfreqapp.db lanhui@118.*.*.118:/home/lanhui/englishpal2/EnglishPal/app/static`
+`pscp wordfreqapp.db lanhui@118.*.*.118:/home/lanhui/englishpal2/EnglishPal/app/db/`
 
 
 
@@ -129,6 +129,28 @@ We welcome feedback on EnglishPal.  Feedback examples:
 EnglishPal's bugs and improvement suggestions are recorded in [Bugzilla](http://118.25.96.118/bugzilla/buglist.cgi?bug_status=__all__&list_id=1302&order=Importance&product=EnglishPal&query_format=specific).  Send (lanhui at zjnu.edu.cn) an email message for opening a Bugzilla account or reporting a bug.
 
 
+## End-to-end testing
+
+We use the Selenium test framework to test our app.
+
+In order to run the test, first we need to download a webdriver executable.
+
+Microsoft Edge's webdriver can be downloaded from [microsoft-edge-tools-webdriver](https://developer.microsoft.com/en-us/microsoft-edge/tools/webdriver/). Make sure the version we download matches the version of the web browser installed on our laptop.
+
+After extracting the downloaded zip file (e.g., edgedriver_win64.zip), rename msedgedriver.exe to MicrosoftWebDriver.exe.
+
+Add MicrosoftWebDriver.exe's path to system's PATH variable.
+
+Install the following dependencies too:
+
+- pip install -U selenium==3.141.0
+- pip install -U urllib3==1.26.2
+
+Run English Pal first, then run the test using pytest as follows: pytest --html=pytest_report.html test_add_word.py
+
+The above command will generate a HTML report file pytest_report.html after finishing executing test_add_word.py.  Note: you need to install pytest-html package first: pip install pytest-html.
+
+You may also want to use [webdriver-manager](https://pypi.org/project/webdriver-manager/) from PyPI, so that you can avoid tediously installing a web driver executable manually.  However, my experience shows that webdriver-manager is too slow.  For example, it took me 16 minutes to run 9 tests, while with the pre-installed web driver executable, it took less than 2 minutes.
 
 ## TODO
 
diff --git a/app/Article.py b/app/Article.py
index df9ac3a..566ceb6 100644
--- a/app/Article.py
+++ b/app/Article.py
@@ -1,6 +1,5 @@
 from WordFreq import WordFreq
 from wordfreqCMD import youdao_link, sort_in_descending_order
-from UseSqlite import InsertQuery, RecordQuery
 import pickle_idea, pickle_idea2
 import os
 import random, glob
@@ -8,18 +7,15 @@ import hashlib
 from datetime import datetime
 from flask import Flask, request, redirect, render_template, url_for, session, abort, flash, get_flashed_messages
 from difficulty import get_difficulty_level_for_user, text_difficulty_level, user_difficulty_level
+from model.article import get_all_articles, get_article_by_id, get_number_of_articles
+import logging
 
-
-path_prefix = '/var/www/wordfreq/wordfreq/'
-path_prefix = './'  # comment this line in deployment
+path_prefix = './'
+db_path_prefix = './db/'  # comment this line in deployment
 
 
 def total_number_of_essays():
-    rq = RecordQuery(path_prefix + 'static/wordfreqapp.db')
-    rq.instructions("SELECT * FROM article")
-    rq.do()
-    result = rq.get_results()
-    return len(result)
+    return get_number_of_articles()
 
 
 def get_article_title(s):
@@ -33,32 +29,36 @@ def get_article_body(s):
 
 
 def get_today_article(user_word_list, visited_articles):
-    rq = RecordQuery(path_prefix + 'static/wordfreqapp.db')
     if visited_articles is None:
         visited_articles = {
             "index" : 0,  # 为 article_ids 的索引
             "article_ids": []  # 之前显示文章的id列表,越后越新
         }
     if visited_articles["index"] > len(visited_articles["article_ids"])-1:  # 生成新的文章,因此查找所有的文章
-        rq.instructions("SELECT * FROM article")
+        result = get_all_articles()
     else:  # 生成阅读过的文章,因此查询指定 article_id 的文章
         if visited_articles["article_ids"][visited_articles["index"]] == 'null':  # 可能因为直接刷新页面导致直接去查询了'null',因此当刷新的页面的时候,需要直接进行“上一篇”操作
             visited_articles["index"] -= 1
             visited_articles["article_ids"].pop()
-        rq.instructions('SELECT * FROM article WHERE article_id=%d' % (visited_articles["article_ids"][visited_articles["index"]]))
-    rq.do()
-    result = rq.get_results()
+        article_id = visited_articles["article_ids"][visited_articles["index"]]
+        result = get_article_by_id(article_id)
     random.shuffle(result)
 
     # Choose article according to reader's level
-    d1 = load_freq_history(path_prefix + 'static/frequency/frequency.p')
+    logging.debug('* get_today_article(): start d1 = ... ')
+    d1 = load_freq_history(user_word_list)
     d2 = load_freq_history(path_prefix + 'static/words_and_tests.p')
+    logging.debug(' ... get_today_article(): get_difficulty_level_for_user() start')
     d3 = get_difficulty_level_for_user(d1, d2)
+    logging.debug(' ... get_today_article(): done')
 
     d = None
     result_of_generate_article = "not found"
+
     d_user = load_freq_history(user_word_list)
+    logging.debug('* get_today_article(): user_difficulty_level() start')
     user_level = user_difficulty_level(d_user, d3)  # more consideration as user's behaviour is dynamic. Time factor should be considered.
+    logging.debug('* get_today_article(): done')
     text_level = 0
     if visited_articles["index"] > len(visited_articles["article_ids"])-1:  # 生成新的文章
         amount_of_visited_articles = len(visited_articles["article_ids"])
@@ -87,8 +87,8 @@ def get_today_article(user_word_list, visited_articles):
     today_article = None
     if d:
         today_article = {
-            "user_level": '%4.2f' % user_level,
-            "text_level": '%4.2f' % text_level,
+            "user_level": '%4.1f' % user_level,
+            "text_level": '%4.1f' % text_level,
             "date": d['date'],
             "article_title": get_article_title(d['text']),
             "article_body": get_article_body(d['text']),
diff --git a/app/Login.py b/app/Login.py
index cd750d1..17d92fa 100644
--- a/app/Login.py
+++ b/app/Login.py
@@ -1,7 +1,6 @@
 import hashlib
 import string
 from datetime import datetime, timedelta
-from UseSqlite import InsertQuery, RecordQuery
 
 def md5(s):
     '''
diff --git a/app/UseSqlite.py b/app/UseSqlite.py
deleted file mode 100644
index ea4baeb..0000000
--- a/app/UseSqlite.py
+++ /dev/null
@@ -1,87 +0,0 @@
-###########################################################################
-# Copyright 2019 (C) Hui Lan <hui.lan@cantab.net>
-# Written permission must be obtained from the author for commercial uses.
-###########################################################################
-
-
-# Reference: Dusty Phillips.  Python 3 Objected-oriented Programming Second Edition. Pages 326-328.
-# Copyright (C) 2019 Hui Lan
-
-import sqlite3
-
-class Sqlite3Template:
-    def __init__(self, db_fname):
-        self.db_fname = db_fname
-
-    def connect(self, db_fname):
-        self.conn = sqlite3.connect(self.db_fname)
-
-    def instructions(self, query_statement):
-        raise NotImplementedError()
-
-    def operate(self):
-        self.conn.row_factory = sqlite3.Row
-        self.results = self.conn.execute(self.query) # self.query is to be given in the child classes
-        self.conn.commit()
-
-    def format_results(self):
-        raise NotImplementedError()
-
-    def do(self):
-        self.connect(self.db_fname)
-        self.instructions(self.query)
-        self.operate()
-
-    def instructions_with_parameters(self, query_statement, parameters):
-        self.query = query_statement
-        self.parameters = parameters
-
-    def do_with_parameters(self):
-        self.connect(self.db_fname)
-        self.instructions_with_parameters(self.query, self.parameters)
-        self.operate_with_parameters()
-
-    def operate_with_parameters(self):
-        self.conn.row_factory = sqlite3.Row
-        self.results = self.conn.execute(self.query, self.parameters) # self.query is to be given in the child classes
-        self.conn.commit()
-
-
-class InsertQuery(Sqlite3Template):
-    def instructions(self, query):
-        self.query = query
-
-
-class RecordQuery(Sqlite3Template):
-    def instructions(self, query):
-        self.query = query
-
-    def format_results(self):
-        output = []
-        for row_dict in self.results.fetchall():
-            lst = []
-            for k in dict(row_dict):
-                lst.append( row_dict[k] )
-            output.append(', '.join(lst))
-        return '\n\n'.join(output)
-
-    def get_results(self):
-        result = []
-        for row_dict in self.results.fetchall():
-            result.append( dict(row_dict) )
-        return result
-
-
-
-if __name__ == '__main__':
-
-    #iq = InsertQuery('RiskDB.db')
-    #iq.instructions("INSERT INTO inspection Values ('FoodSupplies', 'RI2019051301', '2019-05-13', '{}')")
-    #iq.do()
-    #iq.instructions("INSERT INTO inspection Values ('CarSupplies', 'RI2019051302', '2019-05-13', '{[{\"risk_name\":\"elevator\"}]}')")
-    #iq.do()
-
-    rq = RecordQuery('wordfreqapp.db')
-    rq.instructions("SELECT * FROM article WHERE level=3")
-    rq.do()
-    #print(rq.format_results())
diff --git a/app/account_service.py b/app/account_service.py
index a7ed0c4..fd5f7f6 100644
--- a/app/account_service.py
+++ b/app/account_service.py
@@ -1,4 +1,5 @@
 from flask import *
+from markupsafe import escape
 from Login import check_username_availability, verify_user, add_user, get_expiry_date, change_password, WarningMessage
 
 
diff --git a/app/admin_service.py b/app/admin_service.py
index a604b5e..c461af9 100644
--- a/app/admin_service.py
+++ b/app/admin_service.py
@@ -1,5 +1,6 @@
 # System Library
 from flask import *
+from markupsafe import escape
 
 # Personal library
 from Yaml import yml
@@ -37,6 +38,22 @@ def admin():
 
 @adminService.route("/admin/article", methods=["GET", "POST"])
 def article():
+
+    def _make_title_and_content(article_lst):
+        for article in article_lst:
+            text = escape(article.text) # Fix XSS vulnerability, contributed by Xu Xuan
+            article.title = text.split("\n")[0]
+            article.content = '<br/>'.join(text.split("\n")[1:])
+
+
+    def _update_context():
+        article_len = get_number_of_articles()
+        context["article_number"] = article_len
+        context["text_list"] = get_page_articles(_cur_page, _page_size)
+        _articles = get_page_articles(_cur_page, _page_size)
+        _make_title_and_content(_articles)
+        context["text_list"] = _articles
+
     global _cur_page, _page_size
 
     is_admin = check_is_admin()
@@ -44,20 +61,15 @@ def article():
         return is_admin
 
     _article_number = get_number_of_articles()
+
     try:
-        _page_size = min(
-            max(1, int(request.args.get("size", 5))), _article_number
-        )  # 最小的size是1
-        _cur_page = min(
-            max(1, int(request.args.get("page", 1))), _article_number // _page_size + (_article_number % _page_size > 0)
-        )  # 最小的page是1
+        _page_size = min(max(1, int(request.args.get("size", 5))), _article_number)  # 最小的size是1
+        _cur_page = min(max(1, int(request.args.get("page", 1))), _article_number // _page_size + (_article_number % _page_size > 0))  # 最小的page是1
     except ValueError:
-        return "page parmas must be int!"
-    
+        return "page parameters must be integer!"
+
     _articles = get_page_articles(_cur_page, _page_size)
-    for article in _articles:   # 获取每篇文章的title
-        article.title = article.text.split("\n")[0]
-        article.content = '<br/>'.join(article.text.split("\n")[1:])
+    _make_title_and_content(_articles)
     
     context = {
         "article_number": _article_number,
@@ -67,23 +79,16 @@ def article():
         "username": session.get("username"),
     }
 
-    def _update_context():
-        article_len = get_number_of_articles()
-        context["article_number"] = article_len
-        context["text_list"] = get_page_articles(_cur_page, _page_size)
-        _articles = get_page_articles(_cur_page, _page_size)
-        for article in _articles:   # 获取每篇文章的title
-            article.title = article.text.split("\n")[0]
-        context["text_list"] = _articles
 
     if request.method == "GET":
         try:
             delete_id = int(request.args.get("delete_id", 0))
         except:
-            return "Delete article ID must be int!"
+            return "Delete article ID must be integer!"
         if delete_id:  # delete article
             delete_article_by_id(delete_id)
             _update_context()
+
     elif request.method == "POST":
         data = request.form
         content = data.get("content", "")
@@ -97,6 +102,7 @@ def article():
             _update_context()
             title = content.split('\n')[0]
             flash(f'Article added. Title: {title}')
+
     return render_template("admin_manage_article.html", **context)
 
 
diff --git a/app/db/README.txt b/app/db/README.txt
new file mode 100644
index 0000000..bb826a6
--- /dev/null
+++ b/app/db/README.txt
@@ -0,0 +1 @@
+Put wordfreqapp.db here
diff --git a/app/difficulty.py b/app/difficulty.py
index cb93768..1bd8d68 100644
--- a/app/difficulty.py
+++ b/app/difficulty.py
@@ -18,6 +18,7 @@ def load_record(pickle_fname):
     return d
 
 
+ENGLISH_WORD_DIFFICULTY_DICT = {}
 def convert_test_type_to_difficulty_level(d):
     """
     对原本的单词库中的单词进行难度评级
@@ -39,8 +40,10 @@ def convert_test_type_to_difficulty_level(d):
         elif 'BBC' in d[k]:
             result[k] = 8
 
-    return result  # {'apple': 4, ...}
+    global ENGLISH_WORD_DIFFICULTY_DICT
+    ENGLISH_WORD_DIFFICULTY_DICT = result
 
+    return result  # {'apple': 4, ...}
 
 def get_difficulty_level_for_user(d1, d2):
     """
@@ -49,7 +52,11 @@ def get_difficulty_level_for_user(d1, d2):
     在d2的后面添加单词,没有新建一个新的字典
     """
     # TODO: convert_test_type_to_difficulty_level() should not be called every time.  Each word's difficulty level should be pre-computed.
-    d2 = convert_test_type_to_difficulty_level(d2)  # 根据d2的标记评级{'apple': 4, 'abandon': 4, ...}
+    if ENGLISH_WORD_DIFFICULTY_DICT == {}:
+        d2 = convert_test_type_to_difficulty_level(d2)  # 根据d2的标记评级{'apple': 4, 'abandon': 4, ...}
+    else:
+        d2 = ENGLISH_WORD_DIFFICULTY_DICT
+
     stemmer = snowballstemmer.stemmer('english')
 
     for k in d1:  # 用户的词
diff --git a/app/main.py b/app/main.py
index 4e3f829..19bd889 100644
--- a/app/main.py
+++ b/app/main.py
@@ -1,19 +1,19 @@
-#! /usr/bin/python3
-# -*- coding: utf-8 -*-
-
 ###########################################################################
 # Copyright 2019 (C) Hui Lan <hui.lan@cantab.net>
 # Written permission must be obtained from the author for commercial uses.
 ###########################################################################
-from flask import escape
+from flask import abort
+from markupsafe import escape
 from Login import *
 from Article import *
 import Yaml
 from user_service import userService
 from account_service import accountService
 from admin_service import adminService, ADMIN_NAME
+import os
+
 app = Flask(__name__)
-app.secret_key = 'lunch.time!'
+app.secret_key = os.urandom(32)
 
 # 将蓝图注册到Lab app
 app.register_blueprint(userService)
@@ -54,7 +54,6 @@ def appears_in_test(word, d):
     else:
         return ','.join(d[word])
 
-
 @app.route("/mark", methods=['GET', 'POST'])
 def mark_word():
     '''
diff --git a/app/model/__init__.py b/app/model/__init__.py
index 9526313..f5256a2 100644
--- a/app/model/__init__.py
+++ b/app/model/__init__.py
@@ -1,7 +1,7 @@
 from pony.orm import *
 
 db = Database()
-db.bind("sqlite", "../static/wordfreqapp.db", create_db=True)  # bind sqlite file
+db.bind("sqlite", "../db/wordfreqapp.db", create_db=True)  # bind sqlite file
 
 
 class User(db.Entity):
diff --git a/app/model/article.py b/app/model/article.py
index a3b4bf7..bf19ded 100644
--- a/app/model/article.py
+++ b/app/model/article.py
@@ -7,7 +7,7 @@ def add_article(content, source="manual_input", level="5", question="No question
         Article(
             text=content,
             source=source,
-            date=datetime.now().strftime("%-d %b %Y"),  # format style of `5 Oct 2022`
+            date=datetime.now().strftime("%d %b %Y"),  # format style of `5 Oct 2022`
             level=level,
             question=question,
         )
@@ -32,3 +32,17 @@ def get_page_articles(num, size):
             x
             for x in Article.select().order_by(desc(Article.article_id)).page(num, size)
         ]
+
+
+def get_all_articles():
+    articles = []
+    with db_session:
+        for article in Article.select():
+            articles.append(article.to_dict())
+    return articles
+
+
+def get_article_by_id(article_id):
+    with db_session:
+        article = Article.get(article_id=article_id)
+    return [article.to_dict()]
diff --git a/app/static/config.yml b/app/static/config.yml
index 285f31f..7e681fe 100644
--- a/app/static/config.yml
+++ b/app/static/config.yml
@@ -2,13 +2,14 @@
 css:
   item:
     - ../static/css/bootstrap.css
-
+    - ../static/css/highlighted.css
 # 全局引入的js文件地址
 js:
   head: # 在页面加载之前加载
     - ../static/js/jquery.js
     - ../static/js/read.js
     - ../static/js/word_operation.js
+    - ../static/js/checkboxes.js
   bottom: # 在页面加载完之后加载
     - ../static/js/fillword.js
     - ../static/js/highlight.js
diff --git a/app/static/css/highlighted.css b/app/static/css/highlighted.css
new file mode 100644
index 0000000..167f595
--- /dev/null
+++ b/app/static/css/highlighted.css
@@ -0,0 +1,5 @@
+
+.highlighted {
+    color: red;
+    font-weight: normal;
+}
\ No newline at end of file
diff --git a/app/static/js/checkboxes.js b/app/static/js/checkboxes.js
new file mode 100644
index 0000000..297df55
--- /dev/null
+++ b/app/static/js/checkboxes.js
@@ -0,0 +1,5 @@
+function toggleCheckboxSelection(checkStatus) {
+    // used in userpage_post.html
+    const checkBoxes = document.getElementsByName('marked');
+    checkBoxes.forEach((checkbox) => { checkbox.checked = checkStatus;} );
+}
diff --git a/app/static/js/fillword.js b/app/static/js/fillword.js
index b967633..111027a 100644
--- a/app/static/js/fillword.js
+++ b/app/static/js/fillword.js
@@ -1,5 +1,5 @@
-let isRead = true;
-let isChoose = true;
+let isRead = localStorage.getItem('readChecked') !== 'false';  // default to true
+let isChoose = localStorage.getItem('chooseChecked') !== 'false';
 
 function getWord() {
     return window.getSelection ? window.getSelection() : document.selection.createRange().text;
@@ -8,9 +8,17 @@ function getWord() {
 function fillInWord() {
     let word = getWord();
     if (isRead) Reader.read(word, inputSlider.value);
-    if (!isChoose) return;
+    if (!isChoose) {
+        if(isHighlight){
+             const element = document.getElementById("selected-words3");
+             element.value = element.value + " " + word;
+        }
+        return;
+    }
     const element = document.getElementById("selected-words");
+    localStorage.setItem('nowWords', element.value);
     element.value = element.value + " " + word;
+    localStorage.setItem('selectedWords', element.value);
 }
 
 document.getElementById("text-content").addEventListener("click", fillInWord, false);
@@ -24,8 +32,16 @@ inputSlider.oninput = () => {
 
 function onReadClick() {
     isRead = !isRead;
+    localStorage.setItem('readChecked', isRead);
 }
 
 function onChooseClick() {
     isChoose = !isChoose;
+    localStorage.setItem('chooseChecked', isChoose);
 }
+
+// 如果网页刷新,停止播放声音
+if (performance.getEntriesByType("navigation")[0].type == "reload") {
+    Reader.stopRead();
+}
+
diff --git a/app/static/js/highlight.js b/app/static/js/highlight.js
index 0cea31a..9646ff3 100644
--- a/app/static/js/highlight.js
+++ b/app/static/js/highlight.js
@@ -1,4 +1,4 @@
-let isHighlight = true;
+let isHighlight = localStorage.getItem('highlightChecked') !== 'false'; // default to true
 
 function cancelBtnHandler() {
     cancelHighlighting();
@@ -22,62 +22,48 @@ function getWord() {
 
 function highLight() {
     if (!isHighlight) return;
-    let articleContent = document.getElementById("article").innerText; //将原来的.innerText改为.innerHtml,使用innerText会把原文章中所包含的<br>标签去除,导致处理后的文章内容失去了原来的格式
+    let word = (getWord() + "").trim();
+    let articleContent = document.getElementById("article").innerHTML; // innerHTML保留HTML标签来保持部分格式,且适配不同的浏览器
     let pickedWords = document.getElementById("selected-words");  // words picked to the text area
     let dictionaryWords = document.getElementById("selected-words2"); // words appearing in the user's new words list
-    let allWords = "";  //初始化allWords的值,避免进入判断后编译器认为allWords未初始化的问题
-    if(dictionaryWords != null){//增加一个判断,检查生词本里面是否为空,如果为空,allWords只添加选中的单词
-        allWords = pickedWords.value + " " + dictionaryWords.value;
+    let allWords = dictionaryWords === null ? pickedWords.value + " " : pickedWords.value + " " + dictionaryWords.value;
+    highlightWords = document.getElementById("selected-words3");
+    allWords = highlightWords == null ? allWords : allWords + " " + highlightWords.value;
+    const list = allWords.split(" "); // 将所有的生词放入一个list中
+    if(word !== null && word !== "" && word !== " "){
+        let articleContent_fb2 = articleContent;
+        if(localStorage.getItem("nowWords").indexOf(word) !== -1 || localStorage.getItem("nowWords").indexOf(word.toLowerCase()) !== -1){
+            articleContent = articleContent.replace(new RegExp('<span class="highlighted">' + word + '</span>', "gi"), word);
+            pickedWords.value = localStorage.getItem("nowWords").replace(word,"");
+            document.getElementById("article").innerHTML = articleContent;
+            return;
+        }
     }
-    else{
-        allWords = pickedWords.value + " ";
-    }
-    const list = allWords.split(" ");//将所有的生词放入一个list中,用于后续处理
+    let totalSet = new Set();
     for (let i = 0; i < list.length; ++i) {
-        list[i] = list[i].replace(/(^\s*)|(\s*$)/g, ""); //消除单词两边的空字符
+        list[i] = list[i].replace(/(^\W*)|(\W*$)/g, ""); // 消除单词两边的非单词字符
         list[i] = list[i].replace('|', "");
         list[i] = list[i].replace('?', "");
-        if (list[i] !== "" && "<mark>".indexOf(list[i]) === -1 && "</mark>".indexOf(list[i]) === -1) {
-           //将文章中所有出现该单词word的地方改为:"<mark>" + word + "<mark>"。 正则表达式RegExp()中,"\\b"代表单词边界匹配。
-
-            //修改代码
-            let articleContent_fb = articleContent;  //文章副本
-            while(articleContent_fb.toLowerCase().indexOf(list[i].toLowerCase()) !== -1 && list[i]!=""){
-                //找到副本中和list[i]匹配的第一个单词(第一种匹配情况),并赋值给list[i]。
-                const index = articleContent_fb.toLowerCase().indexOf(list[i].toLowerCase());
-                list[i] = articleContent_fb.substring(index, index + list[i].length);
-
-                articleContent_fb = articleContent_fb.substring(index + list[i].length);    // 使用副本中list[i]之后的子串替换掉副本
-                articleContent = articleContent.replace(new RegExp("\\b"+list[i]+"\\b","g"),"<mark>" + list[i] + "</mark>");
-            }
+        if (list[i] != "" && !totalSet.has(list[i])) {
+            // 返回所有匹配单词的集合, 正则表达式RegExp()中, "\b"匹配一个单词的边界, g 表示全局匹配, i 表示对大小写不敏感。
+            let matches = new Set(articleContent.match(new RegExp("\\b" + list[i] + "\\b", "gi")));
+            totalSet = new Set([...totalSet, ...matches]);
         }
     }
+    // 删除所有的"<span class='highlighted'>"标签,防止标签发生嵌套
+    articleContent = articleContent.replace(new RegExp('<span class="highlighted">',"gi"), "")
+    articleContent = articleContent.replace(new RegExp("</span>","gi"), "");
+    // 将文章中所有出现该单词word的地方改为:"<span class='highlighted'>" + word + "</span>"。
+    for (let word of totalSet) {
+        articleContent = articleContent.replace(new RegExp("\\b" + word + "\\b", "g"), "<span class='highlighted'>" + word + "</span>");
+    }
     document.getElementById("article").innerHTML = articleContent;
 }
 
 function cancelHighlighting() {
-    let articleContent = document.getElementById("article").innerText;//将原来的.innerText改为.innerHtml,原因同上
-    let pickedWords = document.getElementById("selected-words");
-    const dictionaryWords = document.getElementById("selected-words2");    
-    const list = pickedWords.value.split(" ");    
-    if (pickedWords != null) {
-        for (let i = 0; i < list.length; ++i) {
-            list[i] = list[i].replace(/(^\s*)|(\s*$)/g, "");
-            if (list[i] !== "") { //原来判断的代码中,替换的内容为“list[i]”这个字符串,这明显是错误的,我们需要替换的是list[i]里的内容
-                articleContent = articleContent.replace(new RegExp("<mark>"+list[i]+"</mark>", "g"), list[i]);
-            }
-        }
-    }
-    if (dictionaryWords != null) {
-        let list2 = pickedWords.value.split(" ");
-        for (let i = 0; i < list2.length; ++i) {
-            list2 = dictionaryWords.value.split(" ");
-            list2[i] = list2[i].replace(/(^\s*)|(\s*$)/g, "");
-            if (list2[i] !== "") { //原来代码中,替换的内容为“list[i]”这个字符串,这明显是错误的,我们需要替换的是list[i]里的内容
-                articleContent = articleContent.replace(new RegExp("<mark>"+list2[i]+"</mark>", "g"), list2[i]);
-            }
-        }
-    }
+    let articleContent = document.getElementById("article").innerHTML;
+    articleContent = articleContent.replace(new RegExp('<span class="highlighted">',"gi"), "")
+    articleContent = articleContent.replace(new RegExp("</span>","gi"), "");
     document.getElementById("article").innerHTML = articleContent;
 }
 
@@ -97,6 +83,7 @@ function toggleHighlighting() {
         isHighlight = true;
         highLight();
     }
+     localStorage.setItem('highlightChecked', isHighlight);
 }
 
-showBtnHandler();
+showBtnHandler();
\ No newline at end of file
diff --git a/app/static/js/read.js b/app/static/js/read.js
index 814f627..c28fd26 100644
--- a/app/static/js/read.js
+++ b/app/static/js/read.js
@@ -9,7 +9,7 @@ var Reader = (function() {
         msg.rate = rate;
         msg.lang = "en-US";
         msg.onboundary = ev => {
-            if (ev.name == "word") {
+            if (ev.name === "word") {
                 current_position = ev.charIndex;
             }
         }
@@ -32,4 +32,4 @@ var Reader = (function() {
         read: read,
         stopRead: stopRead
     };
-})();
+}) ();
diff --git a/app/static/js/word_operation.js b/app/static/js/word_operation.js
index f043cce..dcf38ff 100644
--- a/app/static/js/word_operation.js
+++ b/app/static/js/word_operation.js
@@ -5,15 +5,14 @@ function familiar(theWord) {
     $.ajax({
         type:"GET",
         url:"/" + username + "/" + word + "/familiar",
-        success:function(response){
+        success:function(response) {
             let new_freq = freq - 1;
             const allow_move = document.getElementById("move_dynamiclly").checked;
             if (allow_move) {
-
                 if (new_freq <= 0) {
                     removeWord(theWord);
                 } else {
-                    renderWord({ word: theWord, freq: new_freq });
+                    renderWord({word: theWord, freq: new_freq});
                 }
             } else {
                 if(new_freq <1) {
@@ -33,11 +32,11 @@ function unfamiliar(theWord) {
     $.ajax({
         type:"GET",
         url:"/" + username + "/" + word + "/unfamiliar",
-        success:function(response){
+        success:function(response) {
             let new_freq = parseInt(freq) + 1;
             const allow_move = document.getElementById("move_dynamiclly").checked;
             if (allow_move) {
-                renderWord({ word: theWord, freq: new_freq });
+                renderWord({word: theWord, freq: new_freq});
             } else {
                 $("#freq_" + theWord).text(new_freq);
             }
@@ -51,7 +50,7 @@ function delete_word(theWord) {
     $.ajax({
         type:"GET",
         url:"/" + username + "/" + word + "/del",
-        success:function(response){
+        success:function(response) {
             const allow_move = document.getElementById("move_dynamiclly").checked;
             if (allow_move) {
                 removeWord(theWord);
@@ -114,7 +113,7 @@ function removeWord(word) {
     // 根据词频信息删除元素
     word = word.replace('&amp;', '&');
     const element_to_remove = document.getElementById(`p_${word}`);
-    if (element_to_remove != null) {
+    if (element_to_remove !== null) {
         element_to_remove.remove();
     }
 }
@@ -129,7 +128,7 @@ function renderWord(word) {
     for (const current of container.children) {
         const cur_word = parseWord(current);
         // 找到第一个词频比它小的元素,插入到这个元素前面
-        if (compareWord(cur_word, word) == -1) {
+        if (compareWord(cur_word, word) === -1) {
             container.insertBefore(new_element, current);
             inserted = true;
             break;
@@ -165,17 +164,11 @@ function elementFromString(string) {
  *  当first大于second时返回1
  */
 function compareWord(first, second) {
-    if (first.freq < second.freq) {
-        return -1;
+    if (first.freq !== second.freq) {
+        return first.freq < second.freq ? -1 : 1;
     }
-    if (first.freq > second.freq) {
-        return 1;
-    }
-    if (first.word < second.word) {
-        return -1;
-    }
-    if (first.word > second.word) {
-        return 1;
+    if (first.word !== second.word) {
+        return first.word < second.word ? -1 : 1;
     }
     return 0;
-}
+}
\ No newline at end of file
diff --git a/app/templates/login.html b/app/templates/login.html
index 2507f75..b0806b6 100644
--- a/app/templates/login.html
+++ b/app/templates/login.html
@@ -1,7 +1,7 @@
 {% block body %}
 {% if session['logged_in'] %}
 
-你已登录 <a href="/{{ session['username'] }}">{{ session['username'] }}</a>。 登出点击<a href="/logout">这里</a>。
+你已登录 <a href="/{{ session['username'] }}/userpage">{{ session['username'] }}</a>。 登出点击<a href="/logout">这里</a>。
 
 {% else %}
 <meta charset="utf-8" name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=0.5, maximum-scale=3.0, user-scalable=yes" />
@@ -15,6 +15,10 @@
             alert('输入不能为空!');
             return false;
         }
+        if (password.includes(' ')) {
+            alert('输入不能包含空格!');
+            return false;
+        }
         $.post(
             "/login", {'username': username, 'password': password},
             function (response) {
@@ -32,14 +36,13 @@
 <div class="container">
 
   <section class="signin-heading">
-    <h1>Sign In</h1>
+    <h1>Sign in</h1>
   </section>
 
   <input type="text" placeholder="用户名" class="username" id="username">
   <input type="password" placeholder="密码" class="password"  id="password">
   <button type="button" class="btn" onclick="login()">登录</button>
   <a class="signup" href="/signup">注册</a>
-
 </div>
 
 {% endif %}
diff --git a/app/templates/mainpage_get.html b/app/templates/mainpage_get.html
index 344943d..2a9b8e3 100644
--- a/app/templates/mainpage_get.html
+++ b/app/templates/mainpage_get.html
@@ -34,9 +34,9 @@
         <div class="alert alert-success" role="alert">共有文章 <span class="badge bg-success"> {{ number_of_essays }} </span> 篇</div>
         <p>粘贴1篇文章 (English only)</p>
         <form method="post" action="/">
-            <textarea name="content" rows="10" cols="120"></textarea><br/>
+            <textarea name="content" id="article" rows="10" cols="120"></textarea><br/>
             <input type="submit" value="get文章中的词频"/>
-            <input type="reset" value="清除"/>
+            <input type="reset" value="清除" onclick="clearArticle()"/>
         </form>
         {% if d_len > 0 %}
             <p><b>最常见的词</b></p>
@@ -44,6 +44,7 @@
                 <a href="http://youdao.com/w/eng/{{x[0]}}/#keyfrom=dict2.index">{{x[0]}}</a> {{x[1]}}
             {% endfor %}
         {% endif %}
+        <p class="text-muted">Version: 20240618</p>
         <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js" integrity="sha384-MrcW6ZMFYlzcLA8Nl+NtUVF0sA7MsXsP1UyJoMp4YLEuNSfAP+JcXn/tWtIaxVXM" crossorigin="anonymous"></script>
     </div>
     {{ yml['footer'] | safe }}
@@ -52,5 +53,22 @@
             <script src="{{ js }}" ></script>
         {% endfor %}
     {% endif %}
+<script type="text/javascript">
+    // IIFE, avoid polluting the global scope
+    (function() {
+        const articleInput = document.querySelector('#article');
+        articleInput.value = localStorage.getItem('article') || '';
+
+        articleInput.addEventListener('input', function() {
+            localStorage.setItem('article', articleInput.value);
+        });
+
+        window.clearArticle = function() {
+            localStorage.removeItem('article');
+            articleInput.value = '';
+        };
+    })();
+
+</script>
 </body>
 </html>
diff --git a/app/templates/mainpage_post.html b/app/templates/mainpage_post.html
index 7357457..5df7dd5 100644
--- a/app/templates/mainpage_post.html
+++ b/app/templates/mainpage_post.html
@@ -2,7 +2,7 @@
 <html lang="en">
 <head>
     <meta charset="UTF-8">
-    <title>Title</title>
+    <title>单词词频</title>
 
     {{ yml['header'] | safe }}
     {% if yml['css']['item'] %}
diff --git a/app/templates/reset.html b/app/templates/reset.html
index 3425c97..408e001 100644
--- a/app/templates/reset.html
+++ b/app/templates/reset.html
@@ -12,6 +12,10 @@
                 alert('输入不能为空!');
                 return false;
             }
+            if (old_password.includes(' ') || new_password.includes(' ')) {
+                alert('输入不能包含空格!');
+                return false;
+            }
             if (new_password !== re_new_password) {
                 alert('新密码不匹配,请重新输入');
                 return false;
diff --git a/app/templates/signup.html b/app/templates/signup.html
index 9030d41..6b5db6e 100644
--- a/app/templates/signup.html
+++ b/app/templates/signup.html
@@ -16,6 +16,10 @@ You're logged in already! <a href="/logout">Logout</a>.
                 alert('输入不能为空!');
                 return false;
             }
+            if (password.includes(' ') || password2.includes(' ')) {
+                alert('输入不能包含空格!');
+                return false;
+            }
             if (password !== password2) {
                 alert('确认密码与输入密码不一致!');
                 return false;
@@ -53,7 +57,7 @@ You're logged in already! <a href="/logout">Logout</a>.
 <div class="container">
 
   <section class="signin-heading">
-    <h1>Sign Up</h1>
+    <h1>Sign up</h1>
   </section>
 
   <p><input type="username" id="username" placeholder="输入用户名" class="username"></p>
diff --git a/app/templates/userpage_get.html b/app/templates/userpage_get.html
index 0488aea..e5c8d95 100644
--- a/app/templates/userpage_get.html
+++ b/app/templates/userpage_get.html
@@ -23,44 +23,34 @@
     <title>EnglishPal Study Room for {{ username }}</title>
 
     <style>
-        .shaking {
-            animation: shakes 1600ms ease-in-out;
-        }
+      .shaking {
+          animation: shakes 1600ms ease-in-out;
+      }
 
-        @keyframes shakes {
-            10%, 90% {
-                transform: translate3d(-1px, 0, 0);
-            }
-            20%, 50% {
-                transform: translate3d(+2px, 0, 0);
-            }
-            30%, 70% {
-                transform: translate3d(-4px, 0, 0);
-            }
-            40%, 60% {
-                transform: translate3d(+4px, 0, 0);
-            }
-            50% {
-                transform: translate3d(-4px, 0, 0);
-            }
-        }
+      @keyframes shakes {
+          10%, 90% { transform: translate3d(-1px, 0, 0); }
+          20%, 50% { transform: translate3d(+2px, 0, 0); }
+          30%, 70% { transform: translate3d(-4px, 0, 0); }
+          40%, 60% { transform: translate3d(+4px, 0, 0); }
+          50% { transform: translate3d(-4px, 0, 0); }
+      }
 
-        .lead {
-            font-size: 22px;
-            font-family: Helvetica, sans-serif;
-            white-space: pre-wrap;
-        }
+      .lead{
+          font-size: 22px;
+          font-family: Helvetica, sans-serif;
+          white-space: pre-wrap;
+      }
 
-        .arrow {
-            padding: 0;
-            font-size: 20px;
-            line-height: 21px;
-            display: inline-block;
-        }
+      .arrow {
+	  padding: 0;
+	  font-size: 20px;
+	  line-height: 21px;
+	  display: inline-block;
+      }
 
-        .arrow:hover {
-            cursor: pointer;
-        }
+      .arrow:hover {
+	  cursor: pointer;
+      }
 
     </style>
 </head>
@@ -69,83 +59,72 @@
     <p><b>English Pal for <font id="username" color="red">{{ username }}</font></b>
 
         {% if username ==  admin_name %}
-            <a class="btn btn-secondary" href="/admin" role="button" onclick="stopRead()">管理</a>
+        <a class="btn btn-secondary" href="/admin" role="button" onclick="stopRead()">管理</a>
         {% endif %}
         <a id="quit" class="btn btn-secondary" href="/logout" role="button" onclick="stopRead()">退出</a>
         <a class="btn btn-secondary" href="/reset" role="button" onclick="stopRead()">重设密码</a>
 
     </p>
     {% for message in get_flashed_messages() %}
-        <div class="alert alert-warning alert-dismissible fade show" role="alert">
-            {{ message }}
-            <button type="button" class="btn-close" data-bs-dismiss="alert" aria-label="Close"></button>
-        </div>
+    <div class="alert alert-warning alert-dismissible fade show" role="alert">
+	{{ message }}
+	<button type="button" class="btn-close" data-bs-dismiss="alert" aria-label="Close"></button>
+    </div>
     {% endfor %}
 
-    <button class="arrow" id="load_next_article" onclick="load_next_article();Reader.stopRead()"
-            title="下一篇 Next Article">⇨
-    </button>
-    <button class="arrow" id="load_pre_article" onclick="load_pre_article();Reader.stopRead()" style="display: none"
-            title="上一篇 Previous Article">⇦
-    </button>
+        <button class="arrow" id="load_next_article" onclick="load_next_article();Reader.stopRead()" title="下一篇 Next Article">⇨</button>
+        <button class="arrow" id="load_pre_article" onclick="load_pre_article();Reader.stopRead()" style="display: none" title="上一篇 Previous Article">⇦</button>
 
     <p><b>阅读文章并回答问题</b></p>
     <div id="text-content">
         <div id="found">
-            <div class="alert alert-success" role="alert">According to your word list, your level is <span
-                    class="text-decoration-underline" id="user_level">{{ today_article["user_level"] }}</span> and we
-                have chosen an article with a difficulty level of <span class="text-decoration-underline"
-                                                                        id="text_level">{{ today_article["text_level"] }}</span>
-                for you.
-            </div>
-            <p class="text-muted" id="date">Article added on: {{ today_article["date"] }}</p><br/>
+            <div class="alert alert-success" role="alert">According to your word list, your level is <span class="text-decoration-underline" id="user_level">{{ today_article["user_level"] }}</span>  and we have chosen an article with a difficulty level of <span class="text-decoration-underline" id="text_level">{{ today_article["text_level"] }}</span> for you.</div>
+                <p class="text-muted" id="date">Article added on: {{ today_article["date"] }}</p><br/>
             <div class="p-3 mb-2 bg-light text-dark" style="margin: 0 0.5%;"><br/>
-                <p class="display-6" id="article_title">{{ today_article["article_title"] }}</p><br/>
-                <p class="lead"><font id="article">{{ today_article["article_body"] }}</font></p><br/>
-                <div>
-                    <p><small class="text-muted" id="source">{{ today_article['source'] }}</small></p><br/>
-                </div>
+            <p class="display-6" id="article_title">{{ today_article["article_title"] }}</p><br/>
+            <p class="lead"><font id="article">{{ today_article["article_body"] }}</font></p><br/>
+            <div>
+                <p><small class="text-muted" id="source">{{ today_article['source'] }}</small></p><br/>
+            </div>
 
-                <p><b id="question">{{ today_article['question'] }}</b></p><br/>
+            <p><b id="question">{{ today_article['question'] }}</b></p><br/>
                 <script type="text/javascript">
                     function toggle_visibility(id) { {# https://css-tricks.com/snippets/javascript/showhide-element/#}
                         const e = document.getElementById(id);
-                        if (e.style.display === 'block')
+                        if(e.style.display === 'block')
                             e.style.display = 'none';
                         else
                             e.style.display = 'block';
                     }
                 </script>
                 <button onclick="toggle_visibility('answer');">ANSWER</button>
-                <div id="answer" style="display:none;">{{ today_article['answer'] }}</div>
-                <br/>
+                <div id="answer" style="display:none;">{{ today_article['answer'] }}</div><br/>
             </div>
         </div>
         <div class="alert alert-success" role="alert" id="not_found" style="display:none;">
-            <p class="text-muted"><span class="badge bg-success">Notes:</span><br>No article is currently available for
-                you. You can try again a few times or mark new words in the passage to improve your level.</p>
+            <p class="text-muted"><span class="badge bg-success">Notes:</span><br>No article is currently available for you. You can try again a few times or mark new words in the passage to improve your level.</p>
         </div>
         <div class="alert alert-success" role="alert" id="read_all" style="display:none;">
             <p class="text-muted"><span class="badge bg-success">Notes:</span><br>You've read all the articles.</p>
         </div>
     </div>
 
-    <input type="checkbox" id="highlightCheckbox" onclick="toggleHighlighting()"/>生词高亮
-    <input type="checkbox" id="readCheckbox" onclick="onReadClick()"/>大声朗读
-    <input type="checkbox" id="chooseCheckbox" onclick="onChooseClick()"/>划词入库
+    <input type="checkbox" id="highlightCheckbox" onclick="toggleHighlighting()" />生词高亮
+    <input type="checkbox" id="readCheckbox" onclick="onReadClick()" />大声朗读
+    <input type="checkbox" id="chooseCheckbox" onclick="onChooseClick()" />划词入库
     <div class="range">
         <div class="field">
             <div class="sliderValue">
                 <span id="rangeValue">1×</span>
             </div>
-            <input type="range" id="rangeComponent" min="0.5" max="2" value="1" step="0.25"/>
+            <input type="range" id="rangeComponent" min="0.5" max="2" value="1" step="0.25" />
         </div>
     </div>
     <p><b>收集生词吧</b> (可以在正文中划词,也可以复制黏贴)</p>
     <form method="post" action="/{{ username }}/userpage">
         <textarea name="content" id="selected-words" rows="10" cols="120"></textarea><br/>
         <button class="btn btn-primary btn-lg" type="submit" onclick="Reader.stopRead()">把生词加入我的生词库</button>
-        <button class="btn btn-primary btn-lg" type="reset" onclick="clearSelectedWords()">清除</button>
+        <button class="btn btn-primary btn-lg" type="reset"  onclick="clearSelectedWords()">清除</button>
     </form>
     {% if session.get['thisWord'] %}
         <script type="text/javascript">
@@ -173,10 +152,9 @@
                 {% set freq = x[1] %}
                 {% if session.get('thisWord') == x[0] and session.get('time') == 1 %}
                 {% endif %}
-                <p id='p_{{ word }}' class="new-word">
-                    <a id="word_{{ word }}" class="btn btn-light"
-                       href='http://youdao.com/w/eng/{{ word }}/#keyfrom=dict2.index'
-                       role="button">{{ word }}</a>
+                <p id='p_{{ word }}' class="new-word" >
+                    <a id="word_{{ word }}"  class="btn btn-light" href='http://youdao.com/w/eng/{{ word }}/#keyfrom=dict2.index'
+                    role="button">{{ word }}</a>
                     ( <a id="freq_{{ word }}" title="{{ word }}">{{ freq }}</a> )
                     <a class="btn btn-success" onclick="familiar('{{ word }}')" role="button">熟悉</a>
                     <a class="btn btn-warning" onclick="unfamiliar('{{ word }}')" role="button">不熟悉</a>
@@ -188,6 +166,7 @@
         <input id="selected-words2" type="hidden" value="{{ words }}">
     {% endif %}
 </div>
+<label id="selected-words3" type="hidden"></label>
 {{ yml['footer'] | safe }}
 {% if yml['js']['bottom'] %}
     {% for js in yml['js']['bottom'] %}
@@ -244,78 +223,66 @@
     }
 
 
-    function load_next_article() {
-        $("#load_next_article").prop("disabled", true)
+    function load_next_article(){
         $.ajax({
             url: '/get_next_article/{{username}}',
             dataType: 'json',
-            success: function (data) {
+            success: function(data) {
                 // 更新页面内容
-                if (data['today_article']) {
+                if(data['today_article']){
                     update(data['today_article']);
                     check_pre(data['visited_articles']);
                     check_next(data['result_of_generate_article']);
                 }
-            }, complete: function (xhr, status) {
-                $("#load_next_article").prop("disabled", false)
             }
         });
     }
-
-    function load_pre_article() {
+    function load_pre_article(){
         $.ajax({
             url: '/get_pre_article/{{username}}',
             dataType: 'json',
-            success: function (data) {
+            success: function(data) {
                 // 更新页面内容
-                if (data['today_article']) {
+                if(data['today_article']){
                     update(data['today_article']);
                     check_pre(data['visited_articles']);
                 }
             }
         });
     }
-
-    function update(today_article) {
+    function update(today_article){
         $('#user_level').html(today_article['user_level']);
         $('#text_level').html(today_article["text_level"]);
-        $('#date').html('Article added on: ' + today_article["date"]);
+        $('#date').html('Article added on: '+today_article["date"]);
         $('#article_title').html(today_article["article_title"]);
         $('#article').html(today_article["article_body"]);
         $('#source').html(today_article['source']);
         $('#question').html(today_article["question"]);
         $('#answer').html(today_article["answer"]);
         document.querySelector('#text_level').classList.add('mark'); // highlight text difficult level for 2 seconds
-        setTimeout(() => {
-            document.querySelector('#text_level').classList.remove('mark');
-        }, 2000);
+        setTimeout(() => {document.querySelector('#text_level').classList.remove('mark');}, 2000);
         document.querySelector('#user_level').classList.add('mark'); // do the same thing for user difficulty level
-        setTimeout(() => {
-            document.querySelector('#user_level').classList.remove('mark');
-        }, 2000);
+        setTimeout(() => {document.querySelector('#user_level').classList.remove('mark');}, 2000);
     }
-
-    <!-- 检查是否存在上一篇或下一篇,不存在则对应按钮隐藏-->
-    function check_pre(visited_articles) {
-        if ((visited_articles == '') || (visited_articles['index'] <= 0)) {
+<!-- 检查是否存在上一篇或下一篇,不存在则对应按钮隐藏-->
+    function check_pre(visited_articles){
+        if((visited_articles=='')||(visited_articles['index']<=0)){
             $('#load_pre_article').hide();
             sessionStorage.setItem('pre_page_button', 'display')
-        } else {
+        }else{
             $('#load_pre_article').show();
             sessionStorage.setItem('pre_page_button', 'show')
         }
     }
-
-    function check_next(result_of_generate_article) {
-        if (result_of_generate_article == "found") {
-            $('#found').show();
-            $('#not_found').hide();
+    function check_next(result_of_generate_article){
+        if(result_of_generate_article == "found"){
+            $('#found').show();$('#not_found').hide();
             $('#read_all').hide();
-        } else if (result_of_generate_article == "not found") {
+        }else if(result_of_generate_article == "not found"){
             $('#found').hide();
             $('#not_found').show();
             $('#read_all').hide();
-        } else {
+        }else{
             $('#found').hide();
             $('#not_found').hide();
             $('#read_all').show();
@@ -325,7 +292,7 @@
 </body>
 <style>
     mark {
-        color: #{{ yml['highlight']['color'] }};
+        color: red;
         background-color: rgba(0, 0, 0, 0);
     }
 </style>
diff --git a/app/templates/userpage_post.html b/app/templates/userpage_post.html
index 1163787..94816c5 100644
--- a/app/templates/userpage_post.html
+++ b/app/templates/userpage_post.html
@@ -1,45 +1,50 @@
 <!DOCTYPE html>
 <html lang="en">
-<head>
-    <meta charset="UTF-8">
-    <meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=0.5, maximum-scale=3.0, user-scalable=yes" />
-    <meta name="format-detection" content="telephone=no" />
+    <head>
+       <meta charset="UTF-8">
+       <meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=0.5, maximum-scale=3.0, user-scalable=yes" />
+       <meta name="format-detection" content="telephone=no" />
 
-    {{ yml['header'] | safe }}
-    {% if yml['css']['item'] %}
-        {% for css in yml['css']['item'] %}
-        <link href="{{ css }}" rel="stylesheet">
-        {% endfor %}
-    {% endif %}
-    {% if yml['js']['head'] %}
-        {% for js in yml['js']['head'] %}
-            <script src="{{ js }}" ></script>
-        {% endfor %}
-    {% endif %}
+       {{ yml['header'] | safe }}
+       {% if yml['css']['item'] %}
+         {% for css in yml['css']['item'] %}
+         <link href="{{ css }}" rel="stylesheet">
+         {% endfor %}
+        {% endif %}
+        {% if yml['js']['head'] %}
+         {% for js in yml['js']['head'] %}
+         <script src="{{ js }}" ></script>
+         {% endfor %}
+        {% endif %}
 
-    <title>EnglishPal Study Room for {{username}}</title>
-</head>
-<body>
-     <p>取消勾选认识的单词</p>
-      <form method="post" action="/{{username}}/mark">
-       <input type="submit" name="add-btn" value="加入我的生词簿"/>
-       {% for x in lst %}
-          {% set word = x[0]%}
-        <p>
-            <font color="grey">{{loop.index}}</font>
-            :
-            <a href='http://youdao.com/w/eng/{{word}}/#keyfrom=dict2.index' title={{word}}>{{word}}</a>
-            ({{x[1]}})
-            <input type="checkbox" name="marked" value="{{word}}" checked>
-        </p>
+       <title>EnglishPal Study Room for {{username}}</title>
+    </head>
+    <body>
+      <div class="container-fluid">
+          <p class="mt-md-3">
+               <input type="button" id="btn-cancel-selection" value="取消勾选" onclick="toggleCheckboxSelection(false)" />
+               <input type="button" id="btn-selection" value="全部勾选" onclick="toggleCheckboxSelection(true)" />
+          </p>
+          <form method="post" action="/{{username}}/mark">
+              <button type="submit" name="add-btn" class="btn btn-outline-primary btn-lg" onclick="clearSelectedWords()">加入我的生词簿</button>
+              {% for x in lst %}
+              {% set word = x[0]%}
+              <p>
+                    <font color="grey">{{loop.index}}</font>
+                    :
+                    <a href='http://youdao.com/w/eng/{{word}}/#keyfrom=dict2.index' title={{word}}>{{word}}</a>
+                    ({{x[1]}})
+                    <input type="checkbox" name="marked" value="{{word}}" checked>
+              </p>
 
-       {% endfor %}
-       </form>
-    {{ yml['footer'] | safe }}
-    {% if yml['js']['bottom'] %}
-        {% for js in yml['js']['bottom'] %}
-            <script src="{{ js }}" ></script>
-        {% endfor %}
-    {% endif %}
-</body>
+               {% endfor %}
+           </form>
+           {{ yml['footer'] | safe }}
+           {% if yml['js']['bottom'] %}
+            {% for js in yml['js']['bottom'] %}
+             <script src="{{ js }}" ></script>
+            {% endfor %}
+        {% endif %}
+      </div>
+    </body>
 </html>
diff --git a/app/test/conftest.py b/app/test/conftest.py
index 29f6431..ed4186c 100644
--- a/app/test/conftest.py
+++ b/app/test/conftest.py
@@ -1,6 +1,9 @@
 import pytest
+import sqlite3
+import time
 from selenium import webdriver
-from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
+
+from pathlib import Path
 
 @pytest.fixture
 def URL():
@@ -9,5 +12,24 @@ def URL():
 
 @pytest.fixture
 def driver():
-    my_driver = webdriver.Edge()  # uncomment this line if you wish to run the test on your laptop    
-    return my_driver
+    return webdriver.Edge()  # follow the "End-to-end testing" section in README.md to install the web driver executable
+
+
+@pytest.fixture
+def restore_sqlite_database():
+    '''
+    Automatically restore SQLite database file app/db/wordfreqapp.db
+    using SQL statements from app/static/wordfreqapp.sql
+    '''
+    con = sqlite3.connect('../db/wordfreqapp.db')
+    with con:
+        con.executescript('DROP TABLE IF EXISTS user;')
+        con.executescript('DROP TABLE IF EXISTS article;')
+        con.executescript(open('../static/wordfreqapp.sql', encoding='utf8').read())
+    con.close()
+
+
+@pytest.fixture(autouse=True)
+def restart_englishpal(restore_sqlite_database):
+    (Path(__file__).parent / '../main.py').touch()
+    time.sleep(1)
diff --git a/app/test/helper.py b/app/test/helper.py
new file mode 100644
index 0000000..2b0deec
--- /dev/null
+++ b/app/test/helper.py
@@ -0,0 +1,33 @@
+import uuid
+from selenium.webdriver.support.ui import WebDriverWait
+from selenium.webdriver.support import expected_conditions as EC
+from selenium.common.exceptions import UnexpectedAlertPresentException, NoAlertPresentException
+
+def signup(URL, driver):
+    username = 'TestUser' + str(uuid.uuid1()).split('-')[0].title()
+    password = '[Abc+123]'
+
+    driver.get(URL)
+        
+    elem = driver.find_element_by_link_text('注册')
+    elem.click()
+    
+    elem = driver.find_element_by_id('username')
+    elem.send_keys(username)
+    
+    elem = driver.find_element_by_id('password')
+    elem.send_keys(password)
+
+    elem = driver.find_element_by_id('password2')
+    elem.send_keys(password)    
+    
+    elem = driver.find_element_by_class_name('btn') # 找到"注册"按钮
+    elem.click()
+
+    try:
+        WebDriverWait(driver, 1).until(EC.alert_is_present())
+        driver.switch_to.alert.accept()
+    except (UnexpectedAlertPresentException, NoAlertPresentException):
+        pass
+    
+    return username, password
diff --git a/app/test/test_add_word.py b/app/test/test_add_word.py
index a08c376..6526bf0 100644
--- a/app/test/test_add_word.py
+++ b/app/test/test_add_word.py
@@ -1,76 +1,31 @@
-# -*- coding: utf-8 -*-
-# Run the docker image using the following command:
-# docker run -d -p 4444:4444 selenium/standalone-chrome
-from selenium import webdriver
-from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
-
-import random, time
-import string
-
-driver = webdriver.Remote('http://localhost:4444/wd/hub', DesiredCapabilities.FIREFOX)
-driver.implicitly_wait(10)
-
-HOME_PAGE = 'http://121.4.94.30:91/'
+import time
+from helper import signup
 
 
-def has_punctuation(s):
-    return [c for c in s if c in string.punctuation] != []
-    
-def test_add_word():
+def test_add_word(URL, driver):
     try:
-        driver.get(HOME_PAGE)
-        assert 'English Pal -' in driver.page_source
-    
-        # login
-        elem = driver.find_element_by_link_text('登录')
-        elem.click()
-    
-        uname = 'lanhui'
-        password = 'l0ve1t'
-        elem = driver.find_element_by_name('username')
-        elem.send_keys(uname)
-    
-        elem = driver.find_element_by_name('password')
-        elem.send_keys(password)
-        
-        elem = driver.find_element_by_xpath('//form[1]/p[3]/input[1]') # 找到登录按钮
-        elem.click()
-    
-        assert 'EnglishPal Study Room for ' + uname in  driver.title
-    
-        # get essay content
-        elem = driver.find_element_by_id('text-content')
-        essay_content = elem.text
-    
-        elem = driver.find_element_by_id('selected-words')
-        word = random.choice(essay_content.split())
-        while 'font>' in word or 'br>' in word or 'p>' in word or len(word) < 6 or has_punctuation(word):
-            word = random.choice(essay_content.split())
+        username, password = signup(URL, driver) # sign up a new account and automatically log in
+        time.sleep(1)
 
+        # enter the word in the text area
+        elem = driver.find_element_by_id('selected-words')
+        word = 'devour'
         elem.send_keys(word)
 
-        elem = driver.find_element_by_xpath('//form[1]//input[1]') # 找到get所有词频按钮
-        elem.click()
-    
-        elems = driver.find_elements_by_xpath("//input[@type='checkbox']")
-        for elem in elems:
-            if elem.get_attribute('name') == 'marked':
-                elem.click()
-    
-        elem = driver.find_element_by_name('add-btn') # 找到加入我的生词簿按钮
+        elem = driver.find_element_by_xpath('//form[1]//button[1]') # 找到"把生词加入我的生词库"按钮
+        elem.click()
+
+        elem = driver.find_element_by_name('add-btn') # 找到"加入我的生词簿"按钮
         elem.click()
 
-        driver.refresh()
-        driver.refresh()
-        driver.refresh()        
         elems = driver.find_elements_by_xpath("//p[@class='new-word']/a")
-    
+
         found = 0
         for elem in elems:
             if word in elem.text:
                 found = 1
                 break
-    
+
         assert found == 1
-    finally:    
+    finally:
         driver.quit()
diff --git a/app/test/test_bug528_tangjiao.py b/app/test/test_bug528_tangjiao.py
new file mode 100644
index 0000000..802423c
--- /dev/null
+++ b/app/test/test_bug528_tangjiao.py
@@ -0,0 +1,95 @@
+import pytest
+from selenium import webdriver
+from selenium.webdriver.common.by import By
+from selenium.webdriver.common.keys import Keys
+from selenium.webdriver.support.ui import WebDriverWait
+from selenium.webdriver.support import expected_conditions as EC
+from selenium.common.exceptions import NoSuchElementException, TimeoutException
+
+
+# 测试登录页面输入密码包含空格的情况
+def test_login_password_with_space(driver, URL):
+    try:
+        driver.get(URL+"/login")
+
+        # 输入用户名
+        username_elem = driver.find_element_by_id('username')
+        username_elem.send_keys("test_user")
+
+        # 输入包含空格的密码
+        password_elem = driver.find_element_by_id('password')
+        password_elem.send_keys("password with space")
+
+        # 提交登录表单
+        elem = driver.find_element_by_class_name('btn')  # 找到提交按钮
+        elem.click()
+
+        # 显式等待直到警告框出现
+        WebDriverWait(driver, 10).until(EC.alert_is_present())
+
+        # 检查是否弹出警告框
+        alert = driver.switch_to.alert
+        assert "输入不能包含空格!" in alert.text
+    except (NoSuchElementException, TimeoutException) as e:
+        pytest.fail("页面元素未找到或超时: {}".format(e))
+
+
+# 测试注册页面输入密码包含空格的情况
+
+def test_signup_password_with_space(driver, URL):
+    try:
+        driver.get(URL+"/signup")
+
+        # 输入用户名
+        username_elem = driver.find_element_by_id('username')
+        username_elem.send_keys("new_user")
+
+        # 输入包含空格的密码
+        password_elem = driver.find_element_by_id('password')
+        password_elem.send_keys("password with space")
+
+        # 再次输入密码
+        password2_elem = driver.find_element_by_id('password2')
+        password2_elem.send_keys("password with space")
+
+        # 提交注册表单
+        elem = driver.find_element_by_class_name('btn')  # 找到提交按钮
+        elem.click()
+
+        # 显式等待直到警告框出现
+        WebDriverWait(driver, 10).until(EC.alert_is_present())
+
+        # 检查是否弹出警告框
+        alert = driver.switch_to.alert
+        assert "输入不能包含空格!" in alert.text
+    except (NoSuchElementException, TimeoutException) as e:
+        pytest.fail("页面元素未找到或超时: {}".format(e))
+
+
+
+# 测试重设密码页面输入新密码包含空格的情况
+
+def test_reset_password_with_space(driver, URL):
+    try:
+        driver.get(URL+"/reset")
+
+        # 输入用户名
+        username_elem = driver.find_element_by_id('username')
+        username_elem.send_keys("test_user")
+
+        # 输入包含空格的密码
+        password_elem = driver.find_element_by_id('password')
+        password_elem.send_keys("password with space")
+
+        # 提交重设密码表单
+        elem = driver.find_element_by_class_name('btn')  # 找到提交按钮
+        elem.click()
+
+        # 显式等待直到警告框出现
+        WebDriverWait(driver, 10).until(EC.alert_is_present())
+
+        # 检查是否弹出警告框
+        alert = driver.switch_to.alert
+        assert "输入不能包含空格!" in alert.text
+    except (NoSuchElementException, TimeoutException) as e:
+        pytest.fail("页面元素未找到或超时: {}".format(e))
diff --git a/app/test/test_bug544_tangxinyuan.py b/app/test/test_bug544_tangxinyuan.py
new file mode 100644
index 0000000..2cffdd4
--- /dev/null
+++ b/app/test/test_bug544_tangxinyuan.py
@@ -0,0 +1,55 @@
+import random
+import string
+import time
+
+from selenium.webdriver.common.by import By
+from selenium.webdriver.support.ui import WebDriverWait
+from selenium.webdriver.support import expected_conditions as EC
+
+from helper import signup
+
+
+def has_punctuation(s):
+    return any(c in string.punctuation for c in s)
+
+
+def login(driver, home, uname, password):
+    driver.get(home)
+    WebDriverWait(driver, 10).until(EC.element_to_be_clickable((By.LINK_TEXT, '登录'))).click()
+    driver.find_element(By.ID, 'username').send_keys(uname)
+    driver.find_element(By.ID, 'password').send_keys(password)
+    driver.find_element(By.XPATH, '//button[text()="登录"]').click()
+    WebDriverWait(driver, 10).until(EC.title_is(f"EnglishPal Study Room for {uname}"))
+
+
+def select_valid_word(driver):
+    elem = driver.find_element(By.ID, 'text-content')
+    essay_content = elem.text
+    valid_word = random.choice([word for word in essay_content.split() if len(word) >= 6 and not has_punctuation(
+        word) and 'font>' not in word and 'br>' not in word and 'p>' not in word])
+    driver.find_element(By.ID, 'selected-words').send_keys(valid_word)
+    return valid_word
+
+
+def test_save_selected_word(driver, URL):
+    try:
+        username, password = signup(URL, driver)
+        word = select_valid_word(driver)
+        stored_words = driver.execute_script('return localStorage.getItem("selectedWords");')
+        assert word == stored_words, "Selected word not saved to localStorage correctly"
+        # 退出并重新登录以检查存储的单词
+        driver.find_element(By.LINK_TEXT, '退出').click()
+        driver.execute_script("window.open('');window.close();")
+
+        # 等待一会儿,让浏览器有足够的时间关闭标签页
+        WebDriverWait(driver, 2)
+
+        # 重新打开一个新的标签页
+        driver.execute_script("window.open('');")
+        driver.switch_to.window(driver.window_handles[-1])  # 切换到新打开的标签页
+
+        login(driver, URL, username, password)
+        textarea_content = driver.find_element(By.ID, 'selected-words').get_attribute('value')
+        assert word == textarea_content, "Selected word not preserved after re-login"
+    finally:
+        driver.quit()
diff --git a/app/test/test_bug545_HuangHuiLing.py b/app/test/test_bug545_HuangHuiLing.py
new file mode 100644
index 0000000..21ddeea
--- /dev/null
+++ b/app/test/test_bug545_HuangHuiLing.py
@@ -0,0 +1,44 @@
+import random
+import string
+import time
+from selenium.webdriver.common.by import By
+from selenium.webdriver.support.ui import WebDriverWait
+from selenium.webdriver.support import expected_conditions as EC
+from selenium.webdriver.common.action_chains import ActionChains
+
+from helper import signup
+
+def has_punctuation(s):
+    return any(c in string.punctuation for c in s)
+
+def select_one(driver):
+    elem = driver.find_element(By.ID, 'article')
+    essay_content = elem.text
+    valid_word = random.choice([word for word in essay_content.split() if len(word) >= 6 and not has_punctuation(
+        word) and 'font>' not in word and 'br>' not in word and 'p>' not in word])
+    driver.find_element(By.ID, 'selected-words').send_keys(valid_word)
+    driver.find_element(By.ID, 'article').click()
+    return valid_word
+
+def select_two(driver):
+    word = driver.find_element(By.CLASS_NAME, 'highlighted')
+
+    # 创建ActionChains对象
+    actions = ActionChains(driver)
+    actions.move_to_element(word)
+
+    # 模拟鼠标按下并拖动以选择文本
+    actions.double_click()
+    actions.perform()
+
+
+def test_selected_second_word(driver, URL):
+    try:
+        signup(URL, driver)
+        selected_words = select_one(driver);
+        assert selected_words.strip() != "", "选中的单词被放置框中"
+        select_two(driver)
+        selected_second_words = driver.find_element(By.ID, 'selected-words').get_attribute('value')
+        assert selected_second_words.strip() == "", "选中的单词被删除"
+    finally:
+        driver.quit()
diff --git a/app/test/test_bug546_lixiaofeng.py b/app/test/test_bug546_lixiaofeng.py
new file mode 100644
index 0000000..671094b
--- /dev/null
+++ b/app/test/test_bug546_lixiaofeng.py
@@ -0,0 +1,39 @@
+from selenium.webdriver.common.action_chains import ActionChains
+from helper import signup
+
+
+def test_highlight(driver, URL):
+    try:
+        # 打开网页
+        driver.get(URL)
+        driver.maximize_window()
+
+        # 注册
+        signup(URL, driver)
+
+        # 取消勾选“划词入库按钮”
+        highlight_checkbox = driver.find_element_by_id("chooseCheckbox")
+        driver.execute_script("arguments[0].click();", highlight_checkbox)
+
+        article = driver.find_element_by_id("article")
+
+        # 创建 ActionChains 对象
+        actions = ActionChains(driver)
+
+        # 移动鼠标到起点位置
+        actions.move_to_element(article)
+        # actions.move_to_element_with_offset(article, 50, 100)
+        # 按下鼠标左键
+        actions.click_and_hold()
+        # 拖动鼠标到结束位置
+        actions.move_by_offset(400,50)
+        # 释放鼠标左键
+        actions.release()
+        # 执行操作链
+        actions.perform()
+        # time.sleep(10)
+
+        assert driver.find_elements_by_class_name("highlighted") is not None
+    finally:
+        # 测试结束后关闭浏览器
+        driver.quit()
\ No newline at end of file
diff --git a/app/test/test_bug551_DingZeYu.py b/app/test/test_bug551_DingZeYu.py
new file mode 100644
index 0000000..015fb5a
--- /dev/null
+++ b/app/test/test_bug551_DingZeYu.py
@@ -0,0 +1,37 @@
+import time
+import pytest
+from selenium import webdriver
+from selenium.webdriver import ActionChains
+from selenium.webdriver.common.by import By
+from selenium.webdriver.common.alert import Alert
+from selenium.webdriver.support import expected_conditions as EC
+from selenium.webdriver.support.wait import WebDriverWait
+from helper import signup
+
+def test_bug551(driver, URL):
+    driver.maximize_window()
+    driver.get(URL)
+
+    username, password = signup(URL, driver)
+
+    article = driver.find_element(By.ID, 'article')
+    actions = ActionChains(driver)
+
+    actions.move_to_element(article)
+    actions.click_and_hold()
+    actions.move_by_offset(450, 200)
+    actions.release()
+    actions.perform()
+
+    # 获取选中高亮部分的单词的元素
+    highlighted_words = driver.find_elements(By.CLASS_NAME, 'highlighted')
+
+    # 验证选中部分的单词是否同时应用了需求样式
+    expected_font_weight = "400"  
+
+    for word in highlighted_words:
+        font_weight = word.value_of_css_property("font-weight")
+        assert font_weight == expected_font_weight, f"选中部分的单词的字体样式错误"
+
+    time.sleep(5)
+    driver.quit()
diff --git a/app/test/test_bug553_LinShan.py b/app/test/test_bug553_LinShan.py
new file mode 100644
index 0000000..388f5da
--- /dev/null
+++ b/app/test/test_bug553_LinShan.py
@@ -0,0 +1,58 @@
+from selenium import webdriver
+from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
+from selenium.webdriver.support import expected_conditions as EC
+from selenium import webdriver
+from selenium.webdriver.support.wait import WebDriverWait
+from selenium.webdriver.common.by import By
+from selenium.webdriver.common.keys import Keys
+import logging
+import time
+import pytest
+
+@pytest.mark.parametrize("test_input,expected",
+                         [("‘test1’", "test1"),
+                          ("'test2'", "test2"),
+                          ("“test3”", "test3"),
+                          ("it's", "it's"),
+                          ("hello,I'm linshan", ["hello","i'm","linshan"]),
+                          ("Happy New Year!?", ["happy","new","year"]),
+                          ("My favorite book is 《Harry Potter》。", ["potter","harry","my","favorite","book","is"])])
+def test_bug553_LinShan(test_input,expected, driver, URL):
+    try:
+        # 打开对应地址的网页
+        driver.get(URL)
+
+        # 浏览器最大窗口化
+        driver.maximize_window()
+
+        # 判断网页源代码中是否有English Pal -文字
+        assert 'English Pal -' in driver.page_source
+
+        # 将测试的数据输入到主页的textarea里
+        driver.find_element_by_xpath("//textarea[@name='content']").send_keys(Keys.CONTROL, "a")
+        driver.find_element_by_xpath("//textarea[@name='content']").send_keys(test_input)
+        time.sleep(1)
+
+        # 点击按钮获取单词
+        driver.find_element_by_xpath("//input[@value='get文章中的词频']").click()
+        time.sleep(1)
+
+        # 获取筛选后的单词
+        words = driver.find_elements_by_xpath("//p/a")
+
+        # 遍历获取到的单词,并判断单词与预期的相同
+        for word in words:
+            # 判断单词是否在预期结果中
+            assert word.text in expected
+            
+        # 返回上一页网页
+        driver.find_element_by_xpath("//input[@value='确定并返回']").click()
+        time.sleep(0.1)
+
+    except Exception as e:
+        # 输出异常信息
+        logging.error(e)
+        # 关闭浏览器
+        driver.quit()
+    finally:
+        driver.quit()
diff --git a/app/test/test_bug561_LiangZiyue.py b/app/test/test_bug561_LiangZiyue.py
new file mode 100644
index 0000000..368bc0b
--- /dev/null
+++ b/app/test/test_bug561_LiangZiyue.py
@@ -0,0 +1,27 @@
+import random
+import string
+from selenium.webdriver.common.by import By
+from selenium.webdriver.support.ui import WebDriverWait
+from selenium.webdriver.support import expected_conditions as EC
+
+
+def test_bug561_LiangZiyue(driver, URL):
+    try:
+        driver.get(home)
+        WebDriverWait(driver, 10).until(EC.element_to_be_clickable((By.LINK_TEXT, '登录'))).click()
+        driver.find_element(By.ID, 'username').send_keys("wrr")
+        driver.find_element(By.ID, 'password').send_keys("1234")
+        driver.find_element(By.XPATH, '//button[text()="登录"]').click()
+        ele = driver.find_element(By.XPATH,'//font[@id="article"]')
+        driver.execute_script('arguments[0].scrollIntoView();',ele)
+        action = ActionChains(driver)
+        action.click_and_hold(ele)
+        action.move_by_offset(0,500)
+        action.perform()
+        next_ele = driver.find_element(By.ID,'//button[@id="load_next_article"]')
+        driver.execute_script('arguments[0].scrollIntoView();',next_ele)
+        next_ele.click()
+        driver.execute_script('arguments[0].scrollIntoView();',ele)
+        ele.click()
+    finally:
+        driver.quit()
\ No newline at end of file
diff --git a/app/test/test_stress.py b/app/test/test_stress.py
new file mode 100755
index 0000000..b437b86
--- /dev/null
+++ b/app/test/test_stress.py
@@ -0,0 +1,43 @@
+''' Contributed by Lin Junhong et al. 2023-06.'''
+
+import requests
+import multiprocessing
+import time
+
+def stress(username):
+    try:
+        data = {
+            'username': username,
+            'password': '123123'
+        }
+        headers = {
+            'User-Agent': 'Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.0.0 Mobile Safari/537.36 Edg/114.0.1823.51'
+        }
+        session = requests.session()
+        response = session.post(url='http://127.0.0.1:5000/signup', data=data, headers=headers)
+        print('Sign up ', response.status_code)
+        time.sleep(0.5)
+        response = session.post(url='http://127.0.0.1:5000/login', data=data, headers=headers)
+        print('Sign in ', response.status_code)
+        time.sleep(0.5)
+        response = session.get(url=f'http://127.0.0.1:5000/{username}/userpage', headers=headers)
+        print('User page', response.status_code)
+        time.sleep(0.5)
+        print(session.cookies)
+        for i in range(5):
+            response = session.get(url=f'http://127.0.0.1:5000/get_next_article/{username}', headers=headers, cookies=session.cookies)
+            time.sleep(0.5)
+            print(f'Next page ({i}) [{username}]')
+            print(response.status_code)
+            print(response.json()['today_article']['article_title'])
+    except Exception as e:
+        print(e)
+
+
+if __name__ == '__main__':
+    username = 'Learner'
+    pool = multiprocessing.Pool(processes=10)
+    for i in range(10):
+        pool.apply_async(stress, (f'{username}{i}',))
+    pool.close()
+    pool.join()
diff --git a/app/user_service.py b/app/user_service.py
index 2e5feed..27323b8 100644
--- a/app/user_service.py
+++ b/app/user_service.py
@@ -15,6 +15,9 @@ from wordfreqCMD import sort_in_descending_order
 import pickle_idea
 import pickle_idea2
 
+import logging
+logging.basicConfig(filename='log.txt', format='%(asctime)s %(message)s', level=logging.DEBUG)
+
 # 初始化蓝图
 userService = Blueprint("user_bp", __name__)
 
@@ -32,7 +35,9 @@ def get_next_article(username):
         else:  # 当前不为“null”,直接 index+=1
             visited_articles["index"] += 1
         session["visited_articles"] = visited_articles
+        logging.debug('/get_next_article: start calling get_today_arcile()')
         visited_articles, today_article, result_of_generate_article = get_today_article(user_freq_record, session.get('visited_articles'))
+        logging.debug('/get_next_arcile: done.')
         data = {
             'visited_articles': visited_articles,
             'today_article': today_article,
@@ -129,7 +134,7 @@ def userpage(username):
     user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
 
     if request.method == 'POST':  # when we submit a form
-        content = escape(request.form['content'])
+        content = request.form['content']
         f = WordFreq(content)
         lst = f.get_freq()
         return render_template('userpage_post.html',username=username,lst = lst, yml=Yaml.yml)
@@ -176,7 +181,11 @@ def user_mark_word(username):
         for word in request.form.getlist('marked'):
             lst.append((word, [get_time()]))
         d = pickle_idea2.merge_frequency(lst, lst_history)
-        pickle_idea2.save_frequency_to_pickle(d, user_freq_record)
+        if len(lst_history) > 999:
+            flash('You have way too many words in your difficult-words book. Delete some first.')
+        else:
+            pickle_idea2.save_frequency_to_pickle(d, user_freq_record)
+            flash('Added %s.' % (', '.join(request.form.getlist('marked'))))
         return redirect(url_for('user_bp.userpage', username=username))
     else:
         return 'Under construction'
diff --git a/app/wordfreqCMD.py b/app/wordfreqCMD.py
index dcee74e..feeafbd 100644
--- a/app/wordfreqCMD.py
+++ b/app/wordfreqCMD.py
@@ -4,6 +4,7 @@
 ###########################################################################
 
 import collections
+import html
 import string
 import operator
 import os, sys # 引入模块sys,因为我要用里面的sys.argv列表中的信息来读取命令行参数。
@@ -39,7 +40,8 @@ def file2str(fname):#文件转字符
 
 
 def remove_punctuation(s): # 这里是s是形参 (parameter)。函数被调用时才给s赋值。
-    special_characters = '\_©~<=>+/[]*&$%^@.,?!:;#()"“”—‘’{}|' # 把里面的字符都去掉
+    special_characters = '\_©~<=>+/[]*&$%^@.,?!:;#()"“”—‘’{}|,。?!¥……()、《》:;·' # 把里面的字符都去掉
+    s = html.unescape(s) # 将HTML实体转换为对应的字符,比如<会被识别为小于号
     for c in special_characters:
         s = s.replace(c, ' ') # 防止出现把 apple,apple 移掉逗号后变成 appleapple 情况
     s = s.replace('--', ' ')
@@ -104,7 +106,7 @@ if __name__ == '__main__':
         print('%s\t%d\t%s' % (x[0], x[1], youdao_link(x[0])))#函数导出
 
     # 把频率的结果放result.html中
-    make_html_page(sort_in_descending_order(L), 'result.html') 
+    make_html_page(sort_in_descending_order(L), 'result.html')
 
     print('\nHistory:\n')
     if os.path.exists('frequency.p'):
diff --git a/build.sh b/build.sh
index e313fce..158a86f 100755
--- a/build.sh
+++ b/build.sh
@@ -2,10 +2,7 @@
 
 DEPLOYMENT_DIR=/home/lanhui/englishpal2/EnglishPal
 cd $DEPLOYMENT_DIR
-
-# Install dependencies
-
-pip3 install -r requirements.txt
+pwd
 
 # Stop service
 sudo docker stop EnglishPal
@@ -15,7 +12,7 @@ sudo docker rm EnglishPal
 sudo docker build -t englishpal .
 
 # Run the application
-sudo docker run --restart=always -d --name EnglishPal -p 90:80 -v ${DEPLOYMENT_DIR}/app/static/frequency:/app/static/frequency -v ${DEPLOYMENT_DIR}/app/static/:/app/static/ -t englishpal  # for permanently saving data
+sudo docker run --restart=always -d --name EnglishPal -p 90:80  -v ${DEPLOYMENT_DIR}/app/static/frequency:/app/static/frequency --mount type=volume,src=englishpal-db,target=/app/db -t englishpal # for permanently saving data
 
 # Save space.  Run it after sudo docker run
 sudo docker system prune -a -f