diff --git a/app/pickle_idea2.py b/app/pickle_idea2.py
index 0da55bc..cbee5df 100644
--- a/app/pickle_idea2.py
+++ b/app/pickle_idea2.py
@@ -1,89 +1,147 @@
-###########################################################################
-# Copyright 2019 (C) Hui Lan <hui.lan@cantab.net>
-# Written permission must be obtained from the author for commercial uses.
-###########################################################################
-
-
-# Purpose: dictionary & pickle as a simple means of database.
-# Task: incorporate the functions into wordfreqCMD.py such that it will also show cumulative frequency.
-# Note: unlike pick_idea.py, now the second item is not frequency, but a list of dates.
-
-import pickle
-from datetime import datetime
-
-def lst2dict(lst, d):
-    ''' 
-    Store the information in list lst to dictionary d. 
-    Note: nothing is returned.
-
-    '''
-    for x in lst:
-        word = x[0]
-        dates = x[1]
-        if not word in d:
-            d[word] = dates
-        else:
-            d[word] += dates
-
-def deleteRecord(path,word):
-    with open(path, 'rb') as f:
-        db = pickle.load(f)
-    try:
-        db.pop(word)
-    except KeyError:
-        print("sorry")
-    with open(path, 'wb') as ff:
-            pickle.dump(db, ff)
-
-def dict2lst(d):
-    if len(d) > 0:
-        keys = list(d.keys())
-        if isinstance(d[keys[0]], int):
-            lst = []
-            for k in d:
-                lst.append((k, [datetime.now().strftime('%Y%m%d%H%M')]))
-            return lst
-        elif isinstance(d[keys[0]], list):
-            return list(d.items()) # a list of (key, value) pairs
-
-    return []
-
-def merge_frequency(lst1, lst2):
-    d = {}
-    lst2dict(lst1, d)
-    lst2dict(lst2, d)
-    return d
-
-
-def load_record(pickle_fname):
-    f = open(pickle_fname, 'rb')
-    d = pickle.load(f)
-    f.close()
-    return d
-
-
-def save_frequency_to_pickle(d, pickle_fname):
-    f = open(pickle_fname, 'wb')
-    exclusion_lst = ['one', 'no', 'has', 'had', 'do', 'that', 'have', 'by', 'not', 'but', 'we', 'this', 'my', 'him', 'so', 'or', 'as', 'are', 'it', 'from', 'with', 'be', 'can', 'for', 'an', 'if', 'who', 'whom', 'whose', 'which', 'the', 'to', 'a', 'of', 'and', 'you', 'i', 'he', 'she', 'they', 'me', 'was', 'were', 'is', 'in', 'at', 'on', 'their', 'his', 'her', 's', 'said', 'all', 'did', 'been', 'w']
-    d2 = {}
-    for k in d:
-        if not k in exclusion_lst and not k.isnumeric() and not len(k) < 2:
-            d2[k] = list(sorted(d[k])) # 原先这里是d2[k] = list(sorted(set(d[k])))
-    pickle.dump(d2, f)
-    f.close()
-
-
-
-if __name__ == '__main__':
-
-    lst1 = [('apple',['201910251437', '201910251438']),  ('banana',['201910251439'])]
-    d = {}
-    lst2dict(lst1, d) # d will change
-    save_frequency_to_pickle(d, 'frequency.p') # frequency.p is our database
-
-
-    lst2 = [('banana',['201910251439']), ('orange', ['201910251440', '201910251439'])]
-    d = load_record('frequency.p')
-    lst1 = dict2lst(d)
-    d = merge_frequency(lst2, lst1)
-    print(d)
+###########################################################################
+# Copyright 2019 (C) Hui Lan <hui.lan@cantab.net>
+# Written permission must be obtained from the author for commercial uses.
+###########################################################################
+
+
+# Purpose: dictionary & pickle as a simple means of database.
+# Task: incorporate the functions into wordfreqCMD.py such that it will also show cumulative frequency.
+# Note: unlike pick_idea.py, now the second item is not frequency, but a list of dates.
+
+import pickle
+import requests
+import hashlib
+import random
+from urllib.parse import urlencode
+
+from datetime import datetime
+
+class BaiduContent:
+    APPID = '20200314000398337'  # 将'您的APPID'替换为实际的APPID
+    KEY = 'uZ6Sdwz_V1zu9q1peowk'     # 将'您的密钥'替换为实际的API密钥
+
+def generate_sign(appid, q, salt, key):
+    sign_str = appid + q + str(salt) + key
+    sign = hashlib.md5(sign_str.encode('utf-8')).hexdigest()
+    return sign
+def is_valid_word(word):
+    url = "https://fanyi-api.baidu.com/api/trans/vip/translate"
+    salt = random.randint(32768, 65536)
+    sign = generate_sign(BaiduContent.APPID, word, salt, BaiduContent.KEY)
+
+    params = {
+        'q': word,
+        'from': 'en',
+        'to': 'zh',
+        'appid': BaiduContent.APPID,
+        'salt': salt,
+        'sign': sign
+    }
+
+    headers = {'Content-Type': "application/x-www-form-urlencoded"}
+    data = urlencode(params).encode('utf-8')
+
+    try:
+        response = requests.post(url, data=data, headers=headers)
+        if response.status_code == 200:
+            data = response.json()
+            # print(data['trans_result'][0]['dst'])
+            # 检查是否含有翻译结果，并判断翻译后的文本是否与原文不同
+            if 'trans_result' in data and data['trans_result'][0]['dst'] != word:
+                return True
+            else:
+                return False
+        else:
+            return False
+    except requests.RequestException:
+        return False
+
+def lst2dict(lst, d):
+    ''' 
+    Store the information in list lst to dictionary d. 
+    Note: nothing is returned.
+
+    '''
+    for x in lst:
+        word = x[0]
+        dates = x[1]
+        if not word in d:
+            d[word] = dates
+        else:
+            d[word] += dates
+
+def deleteRecord(path,word):
+    with open(path, 'rb') as f:
+        db = pickle.load(f)
+    try:
+        db.pop(word)
+    except KeyError:
+        print("sorry")
+    with open(path, 'wb') as ff:
+            pickle.dump(db, ff)
+
+def dict2lst(d):
+    if len(d) > 0:
+        keys = list(d.keys())
+        if isinstance(d[keys[0]], int):
+            lst = []
+            for k in d:
+                lst.append((k, [datetime.now().strftime('%Y%m%d%H%M')]))
+            return lst
+        elif isinstance(d[keys[0]], list):
+            return list(d.items()) # a list of (key, value) pairs
+
+    return []
+
+def merge_frequency(lst1, lst2):
+    d = {}
+    lst2dict(lst1, d)
+    lst2dict(lst2, d)
+    return d
+
+
+def load_record(pickle_fname):
+    f = open(pickle_fname, 'rb')
+    d = pickle.load(f)
+    f.close()
+    return d
+
+    # exclusion_lst = ['one', 'no', 'has', 'had', 'do', 'that', 'have', 'by', 'not', 'but', 'we', 'this', 'my', 'him', 'so', 'or', 'as', 'are', 'it', 'from', 'with', 'be', 'can', 'for', 'an', 'if', 'who', 'whom', 'whose', 'which', 'the', 'to', 'a', 'of', 'and', 'you', 'i', 'he', 'she', 'they', 'me', 'was', 'were', 'is', 'in', 'at', 'on', 'their', 'his', 'her', 's', 'said', 'all', 'did', 'been', 'w']
+def save_frequency_to_pickle(d, pickle_fname):
+    with open(pickle_fname, 'wb') as f:  # 使用 with 语句自动处理文件关闭
+        exclusion_lst = []
+        d2 = {}
+        illegal = False  # 标记是否合法
+        added = False
+        for k in d:
+            if k not in exclusion_lst and not k.isnumeric():
+                if is_valid_word(k):  # 只有当单词不合法时进行标记
+                    d2[k] = list(sorted(d[k]))
+                    added =True
+                else:
+                    illegal = True  # 标记至少处理了一个有效单词
+
+        if illegal:
+            if not added:
+                pickle.dump({}, f)
+            else:
+                pickle.dump(d2, f)
+            return 0  # 返回0表示成功处理存在非法单词
+        else:
+            pickle.dump(d2, f)
+            return 1  # 返回1表示成功处理并保存至少一个单词
+
+
+if __name__ == '__main__':
+
+    lst1 = [('apple',['201910251437', '201910251438']),  ('banana',['201910251439'])]
+    d = {}
+    lst2dict(lst1, d) # d will change
+    save_frequency_to_pickle(d, 'frequency.p') # frequency.p is our database
+
+
+    lst2 = [('banana',['201910251439']), ('orange', ['201910251440', '201910251439'])]
+    d = load_record('frequency.p')
+    lst1 = dict2lst(d)
+    d = merge_frequency(lst2, lst1)
+    print(d)
diff --git a/app/user_service.py b/app/user_service.py
index 27323b8..55fa9a5 100644
--- a/app/user_service.py
+++ b/app/user_service.py
@@ -1,199 +1,202 @@
-from datetime import datetime
-from admin_service import ADMIN_NAME
-from flask import *
-
-# from app import Yaml
-# from app.Article import get_today_article, load_freq_history
-# from app.WordFreq import WordFreq
-# from app.wordfreqCMD import sort_in_descending_order
-
-import Yaml
-from Article import get_today_article, load_freq_history
-from WordFreq import WordFreq
-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__)
-
-path_prefix = '/var/www/wordfreq/wordfreq/'
-path_prefix = './'  # comment this line in deployment
-
-@userService.route("/get_next_article/<username>",methods=['GET','POST'])
-def get_next_article(username):
-    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
-    session['old_articleID'] = session.get('articleID')
-    if request.method == 'GET':
-        visited_articles = session.get("visited_articles")
-        if visited_articles['article_ids'][-1] == "null":  # 如果当前还是“null”，则将“null”pop出来,无需index+=1
-            visited_articles['article_ids'].pop()
-        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,
-            'result_of_generate_article': result_of_generate_article
-        }
-    else:
-        return 'Under construction'
-    return json.dumps(data)
-
-@userService.route("/get_pre_article/<username>",methods=['GET'])
-def get_pre_article(username):
-    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
-    if request.method == 'GET':
-        visited_articles = session.get("visited_articles")
-        if(visited_articles["index"]==0):
-            data=''
-        else:
-            visited_articles["index"] -= 1  # 上一篇，index-=1
-            if visited_articles['article_ids'][-1] == "null":  # 如果当前还是“null”，则将“null”pop出来
-                visited_articles['article_ids'].pop()
-            session["visited_articles"] = visited_articles
-            visited_articles, today_article, result_of_generate_article = get_today_article(user_freq_record, session.get('visited_articles'))
-            data = {
-                'visited_articles': visited_articles,
-                'today_article': today_article,
-                'result_of_generate_article':result_of_generate_article
-            }
-        return json.dumps(data)
-
-@userService.route("/<username>/<word>/unfamiliar", methods=['GET', 'POST'])
-def unfamiliar(username, word):
-    '''
-
-    :param username:
-    :param word:
-    :return:
-    '''
-    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
-    pickle_idea.unfamiliar(user_freq_record, word)
-    session['thisWord'] = word  # 1. put a word into session
-    session['time'] = 1
-    return "success"
-
-
-@userService.route("/<username>/<word>/familiar", methods=['GET', 'POST'])
-def familiar(username, word):
-    '''
-
-    :param username:
-    :param word:
-    :return:
-    '''
-    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
-    pickle_idea.familiar(user_freq_record, word)
-    session['thisWord'] = word  # 1. put a word into session
-    session['time'] = 1
-    return "success"
-
-
-@userService.route("/<username>/<word>/del", methods=['GET', 'POST'])
-def deleteword(username, word):
-    '''
-    删除单词
-    :param username: 用户名
-    :param word: 单词
-    :return: 重定位到用户界面
-    '''
-    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
-    pickle_idea2.deleteRecord(user_freq_record, word)
-    # 模板userpage_get.html中删除单词是异步执行，而flash的信息后续是同步执行的，所以注释这段代码；同时如果这里使用flash但不提取信息，则会影响 signup.html的显示。bug复现：删除单词后，点击退出，点击注册，注册页面就会出现提示信息
-    # flash(f'{word} is no longer in your word list.')
-    return "success"
-
-
-@userService.route("/<username>/userpage", methods=['GET', 'POST'])
-def userpage(username):
-    '''
-    用户界面
-    :param username: 用户名
-    :return: 返回用户界面
-    '''
-    # 未登录，跳转到未登录界面
-    if not session.get('logged_in'):
-        return render_template('not_login.html')
-
-    # 用户过期
-    user_expiry_date = session.get('expiry_date')
-    if datetime.now().strftime('%Y%m%d') > user_expiry_date:
-        return render_template('expiry.html', expiry_date=user_expiry_date)
-
-    # 获取session里的用户名
-    username = session.get('username')
-
-    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
-
-    if request.method == 'POST':  # when we submit a form
-        content = request.form['content']
-        f = WordFreq(content)
-        lst = f.get_freq()
-        return render_template('userpage_post.html',username=username,lst = lst, yml=Yaml.yml)
-
-    elif request.method == 'GET':  # when we load a html page
-        d = load_freq_history(user_freq_record)
-        lst = pickle_idea2.dict2lst(d)
-        lst2 = []
-        for t in lst:
-            lst2.append((t[0], len(t[1])))
-        lst3 = sort_in_descending_order(lst2)
-        words = ''
-        for x in lst3:
-            words += x[0] + ' '
-        visited_articles, today_article, result_of_generate_article = get_today_article(user_freq_record, session.get('visited_articles'))
-        session['visited_articles'] = visited_articles
-        # 通过 today_article，加载前端的显示页面
-        return render_template('userpage_get.html',
-                               admin_name=ADMIN_NAME,
-                               username=username,
-                               session=session,
-                               # flashed_messages=get_flashed_messages(), 仅有删除单词的时候使用到flash，而删除单词是异步执行，这里的信息提示是同步执行，所以就没有存在的必要了
-                               today_article=today_article,
-                               result_of_generate_article=result_of_generate_article,
-                               d_len=len(d),
-                               lst3=lst3,
-                               yml=Yaml.yml,
-                               words=words)
-
-@userService.route("/<username>/mark", methods=['GET', 'POST'])
-def user_mark_word(username):
-    '''
-    标记单词
-    :param username: 用户名
-    :return: 重定位到用户界面
-    '''
-    username = session[username]
-    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
-    if request.method == 'POST':
-        # 提交标记的单词
-        d = load_freq_history(user_freq_record)
-        lst_history = pickle_idea2.dict2lst(d)
-        lst = []
-        for word in request.form.getlist('marked'):
-            lst.append((word, [get_time()]))
-        d = pickle_idea2.merge_frequency(lst, lst_history)
-        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'
-
-def get_time():
-    '''
-    获取当前时间
-    :return: 当前时间
-    '''
-    return datetime.now().strftime('%Y%m%d%H%M')  # upper to minutes
-
+from datetime import datetime
+from admin_service import ADMIN_NAME
+from flask import *
+
+# from app import Yaml
+# from app.Article import get_today_article, load_freq_history
+# from app.WordFreq import WordFreq
+# from app.wordfreqCMD import sort_in_descending_order
+
+import Yaml
+from Article import get_today_article, load_freq_history
+from WordFreq import WordFreq
+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__)
+
+path_prefix = '/var/www/wordfreq/wordfreq/'
+path_prefix = './'  # comment this line in deployment
+
+@userService.route("/get_next_article/<username>",methods=['GET','POST'])
+def get_next_article(username):
+    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
+    session['old_articleID'] = session.get('articleID')
+    if request.method == 'GET':
+        visited_articles = session.get("visited_articles")
+        if visited_articles['article_ids'][-1] == "null":  # 如果当前还是“null”，则将“null”pop出来,无需index+=1
+            visited_articles['article_ids'].pop()
+        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,
+            'result_of_generate_article': result_of_generate_article
+        }
+    else:
+        return 'Under construction'
+    return json.dumps(data)
+
+@userService.route("/get_pre_article/<username>",methods=['GET'])
+def get_pre_article(username):
+    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
+    if request.method == 'GET':
+        visited_articles = session.get("visited_articles")
+        if(visited_articles["index"]==0):
+            data=''
+        else:
+            visited_articles["index"] -= 1  # 上一篇，index-=1
+            if visited_articles['article_ids'][-1] == "null":  # 如果当前还是“null”，则将“null”pop出来
+                visited_articles['article_ids'].pop()
+            session["visited_articles"] = visited_articles
+            visited_articles, today_article, result_of_generate_article = get_today_article(user_freq_record, session.get('visited_articles'))
+            data = {
+                'visited_articles': visited_articles,
+                'today_article': today_article,
+                'result_of_generate_article':result_of_generate_article
+            }
+        return json.dumps(data)
+
+@userService.route("/<username>/<word>/unfamiliar", methods=['GET', 'POST'])
+def unfamiliar(username, word):
+    '''
+
+    :param username:
+    :param word:
+    :return:
+    '''
+    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
+    pickle_idea.unfamiliar(user_freq_record, word)
+    session['thisWord'] = word  # 1. put a word into session
+    session['time'] = 1
+    return "success"
+
+
+@userService.route("/<username>/<word>/familiar", methods=['GET', 'POST'])
+def familiar(username, word):
+    '''
+
+    :param username:
+    :param word:
+    :return:
+    '''
+    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
+    pickle_idea.familiar(user_freq_record, word)
+    session['thisWord'] = word  # 1. put a word into session
+    session['time'] = 1
+    return "success"
+
+
+@userService.route("/<username>/<word>/del", methods=['GET', 'POST'])
+def deleteword(username, word):
+    '''
+    删除单词
+    :param username: 用户名
+    :param word: 单词
+    :return: 重定位到用户界面
+    '''
+    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
+    pickle_idea2.deleteRecord(user_freq_record, word)
+    # 模板userpage_get.html中删除单词是异步执行，而flash的信息后续是同步执行的，所以注释这段代码；同时如果这里使用flash但不提取信息，则会影响 signup.html的显示。bug复现：删除单词后，点击退出，点击注册，注册页面就会出现提示信息
+    # flash(f'{word} is no longer in your word list.')
+    return "success"
+
+
+@userService.route("/<username>/userpage", methods=['GET', 'POST'])
+def userpage(username):
+    '''
+    用户界面
+    :param username: 用户名
+    :return: 返回用户界面
+    '''
+    # 未登录，跳转到未登录界面
+    if not session.get('logged_in'):
+        return render_template('not_login.html')
+
+    # 用户过期
+    user_expiry_date = session.get('expiry_date')
+    if datetime.now().strftime('%Y%m%d') > user_expiry_date:
+        return render_template('expiry.html', expiry_date=user_expiry_date)
+
+    # 获取session里的用户名
+    username = session.get('username')
+
+    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
+
+    if request.method == 'POST':  # when we submit a form
+        content = request.form['content']
+        f = WordFreq(content)
+        lst = f.get_freq()
+        return render_template('userpage_post.html',username=username,lst = lst, yml=Yaml.yml)
+
+    elif request.method == 'GET':  # when we load a html page
+        d = load_freq_history(user_freq_record)
+        lst = pickle_idea2.dict2lst(d)
+        lst2 = []
+        for t in lst:
+            lst2.append((t[0], len(t[1])))
+        lst3 = sort_in_descending_order(lst2)
+        words = ''
+        for x in lst3:
+            words += x[0] + ' '
+        visited_articles, today_article, result_of_generate_article = get_today_article(user_freq_record, session.get('visited_articles'))
+        session['visited_articles'] = visited_articles
+        # 通过 today_article，加载前端的显示页面
+        return render_template('userpage_get.html',
+                               admin_name=ADMIN_NAME,
+                               username=username,
+                               session=session,
+                               # flashed_messages=get_flashed_messages(), 仅有删除单词的时候使用到flash，而删除单词是异步执行，这里的信息提示是同步执行，所以就没有存在的必要了
+                               today_article=today_article,
+                               result_of_generate_article=result_of_generate_article,
+                               d_len=len(d),
+                               lst3=lst3,
+                               yml=Yaml.yml,
+                               words=words)
+
+@userService.route("/<username>/mark", methods=['GET', 'POST'])
+def user_mark_word(username):
+    '''
+    标记单词
+    :param username: 用户名
+    :return: 重定位到用户界面
+    '''
+    username = session[username]
+    user_freq_record = path_prefix + 'static/frequency/' + 'frequency_%s.pickle' % (username)
+    if request.method == 'POST':
+        # 提交标记的单词
+        d = load_freq_history(user_freq_record)
+        lst_history = pickle_idea2.dict2lst(d)
+        lst = []
+        for word in request.form.getlist('marked'):
+            lst.append((word, [get_time()]))
+        d = pickle_idea2.merge_frequency(lst, lst_history)
+        if len(lst_history) > 999:
+            flash('You have way too many words in your difficult-words book. Delete some first.')
+        else:
+
+            if pickle_idea2.save_frequency_to_pickle(d, user_freq_record):
+                flash('Added %s.' % (', '.join(request.form.getlist('marked'))))
+            else:
+                flash('%s.存在非法单词' % (', '.join(request.form.getlist('marked'))))
+        return redirect(url_for('user_bp.userpage', username=username))
+    else:
+        return 'Under construction'
+
+def get_time():
+    '''
+    获取当前时间
+    :return: 当前时间
+    '''
+    return datetime.now().strftime('%Y%m%d%H%M')  # upper to minutes
+