diff --git a/app/Login.py b/app/Login.py
index 2e2cecd..d3d609e 100644
--- a/app/Login.py
+++ b/app/Login.py
@@ -5,11 +5,11 @@ from UseSqlite import InsertQuery, RecordQuery
 
 
 def md5(s):
-    '''
+    """
     MD5摘要
     :param str: 字符串
     :return: 经MD5以后的字符串
-    '''
+    """
     h = hashlib.md5(s.encode(encoding='utf-8'))
     return h.hexdigest()
 
@@ -46,17 +46,17 @@ def check_username_availability(username):
 
 
 def change_password(username, old_password, new_password):
-    '''
+    """
     修改密码
     :param username: 用户名
     :param old_password: 旧的密码
     :param new_password: 新密码
     :return: 修改成功:True 否则:False
-    '''
+    """
     if not verify_user(username, old_password):  # 旧密码错误
         return False
     # 将用户名和密码一起加密，以免暴露不同用户的相同密码
-    if verify_pass(new_password, old_password):  #新旧密码一致
+    if verify_pass(new_password, old_password):  # 新旧密码一致
         return False
     update_password_by_username(username, new_password)
     return True
@@ -69,6 +69,7 @@ def get_expiry_date(username):
     else:
         return user.expiry_date
 
+
 class UserName:
     def __init__(self, username):
         self.username = username
diff --git a/app/UseSqlite.py b/app/UseSqlite.py
index ea4baeb..90d5dae 100644
--- a/app/UseSqlite.py
+++ b/app/UseSqlite.py
@@ -9,6 +9,7 @@
 
 import sqlite3
 
+
 class Sqlite3Template:
     def __init__(self, db_fname):
         self.db_fname = db_fname
@@ -72,7 +73,6 @@ class RecordQuery(Sqlite3Template):
         return result
 
 
-
 if __name__ == '__main__':
 
     #iq = InsertQuery('RiskDB.db')
diff --git a/app/WordFreq.py b/app/WordFreq.py
index 3620a41..ffdc246 100644
--- a/app/WordFreq.py
+++ b/app/WordFreq.py
@@ -6,6 +6,7 @@
 from wordfreqCMD import remove_punctuation, freq, sort_in_descending_order
 import string
 
+
 class WordFreq:
     def __init__(self, s):
         self.s = remove_punctuation(s)
diff --git a/app/Yaml.py b/app/Yaml.py
index 00974aa..01fb184 100644
--- a/app/Yaml.py
+++ b/app/Yaml.py
@@ -1,10 +1,10 @@
-'''
+"""
 Yaml.py
 配置文件包括:
     ./static/config.yml
     ./layout/partial/header.html
     ./layout/partial/footer.html
-'''
+"""
 import yaml as YAML
 import os
 
@@ -15,7 +15,7 @@ ymlPath = path_prefix + 'static/config.yml'
 
 # partial文件夹路径
 partialPath = path_prefix + 'layout/partial/'
-f = open(ymlPath, 'r', encoding='utf-8') # 以'UTF-8'格式打开YAML文件
+f = open(ymlPath, 'r', encoding='utf-8')  # 以'UTF-8'格式打开YAML文件
 cont = f.read()  # 以文本形式读取YAML
 
 yml = YAML.load(cont, Loader=YAML.FullLoader)  # 加载YAML
diff --git a/app/account_service.py b/app/account_service.py
index 7259e15..eb396ca 100644
--- a/app/account_service.py
+++ b/app/account_service.py
@@ -8,10 +8,10 @@ accountService = Blueprint("accountService", __name__)
 ### Sign-up, login, logout ###
 @accountService.route("/signup", methods=['GET', 'POST'])
 def signup():
-    '''
+    """
     注册
     :return: 根据注册是否成功返回不同界面
-    '''
+    """
     if request.method == 'GET':
         # GET方法直接返回注册页面
         return render_template('signup.html')
@@ -19,12 +19,12 @@ def signup():
         # POST方法需判断是否注册成功，再根据结果返回不同的内容
         username = escape(request.form['username'])
         password = escape(request.form['password'])
-        
-        #! 添加如下代码为了过滤注册时的非法字符
+
+        # ! 添加如下代码为了过滤注册时的非法字符
         warn = WarningMessage(username)
         if str(warn) != 'OK':
             return jsonify({'status': '3', 'warn': str(warn)})
-        
+
         available = check_username_availability(username)
         if not available: # 用户名不可用
             return jsonify({'status': '0'})
@@ -45,10 +45,10 @@ def signup():
 
 @accountService.route("/login", methods=['GET', 'POST'])
 def login():
-    '''
+    """
     登录
     :return: 根据登录是否成功返回不同页面
-    '''
+    """
     if request.method == 'GET':
         # GET请求
         return render_template('login.html')
@@ -73,10 +73,10 @@ def login():
 
 @accountService.route("/logout", methods=['GET', 'POST'])
 def logout():
-    '''
+    """
     登出
     :return: 重定位到主界面
-    '''
+    """
     # 将session标记为登出状态
     session['logged_in'] = False
     return redirect(url_for('mainpage'))
@@ -84,10 +84,10 @@ def logout():
 
 @accountService.route("/reset", methods=['GET', 'POST'])
 def reset():
-    '''
+    """
     重设密码
     :return: 返回适当的页面
-    '''
+    """
     # 下列方法用于防止未登录状态下的修改密码
     if not session.get('logged_in'):
         return render_template('login.html')
@@ -101,9 +101,9 @@ def reset():
         # POST请求用于提交修改后信息
         old_password = escape(request.form['old-password'])
         new_password = escape(request.form['new-password'])
-        flag = change_password(username, old_password, new_password) # flag表示是否修改成功
+        flag = change_password(username, old_password, new_password)  # flag表示是否修改成功
         if flag:
             session['logged_in'] = False
-            return jsonify({'status':'1'})  # 修改成功
+            return jsonify({'status': '1'})  # 修改成功
         else:
-            return jsonify({'status':'2'})  # 修改失败
+            return jsonify({'status': '2'})  # 修改失败
diff --git a/app/admin_service.py b/app/admin_service.py
index a604b5e..959db6b 100644
--- a/app/admin_service.py
+++ b/app/admin_service.py
@@ -52,7 +52,7 @@ def article():
             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 params must be int!"
     
     _articles = get_page_articles(_cur_page, _page_size)
     for article in _articles:   # 获取每篇文章的title
diff --git a/app/difficulty.py b/app/difficulty.py
index 03d3bfa..d500cca 100644
--- a/app/difficulty.py
+++ b/app/difficulty.py
@@ -65,10 +65,10 @@ def get_difficulty_level_for_user(d1, d2):
 
 
 def revert_dict(d):
-    '''
+    """
     In d, word is the key, and value is a list of dates.
     In d2 (the returned value of this function), time is the key, and the value is a list of words picked at that time.
-    '''
+    """
     d2 = {}
     for k in d:
         if type(d[k]) is list:  # d[k] is a list of dates.
@@ -80,7 +80,7 @@ def revert_dict(d):
 
         for time_info in lst:
             date = time_info[:10]  # until hour
-            if not date in d2:
+            if date not in d2:
                 d2[date] = [k]
             else:
                 d2[date].append(k)
@@ -105,7 +105,7 @@ def user_difficulty_level(d_user, d):
             word = t[0]
             hard = t[1]
             # print('WORD %s HARD %4.2f' % (word, hard))
-            geometric = geometric * (hard)
+            geometric = geometric * hard
             count += 1
             if count >= 10:
                 return geometric ** (1 / count)
@@ -131,7 +131,7 @@ def text_difficulty_level(s, d):
     for t in lst2:
         word = t[0]
         hard = t[1]
-        geometric = geometric * (hard)
+        geometric = geometric * hard
         count += 1
         if count >= 20:  # we look for n most difficult words
             return geometric ** (1 / count)
diff --git a/app/main.py b/app/main.py
index 6308f3d..2267dce 100644
--- a/app/main.py
+++ b/app/main.py
@@ -23,33 +23,34 @@ app.register_blueprint(adminService)
 path_prefix = '/var/www/wordfreq/wordfreq/'
 path_prefix = './'  # comment this line in deployment
 
+
 def get_random_image(path):
-    '''
+    """
     返回随机图
     :param path: 图片文件(JPEG格式)，不包含后缀名
     :return:
-    '''
+    """
     img_path = random.choice(glob.glob(os.path.join(path, '*.jpg')))
 
     return img_path[img_path.rfind('/static'):]
 
 
 def get_random_ads():
-    '''
+    """
     返回随机广告
     :return: 一个广告(包含HTML标签)
-    '''
+    """
     return random.choice(['个性化分析精准提升', '你的专有单词本', '智能捕捉阅读弱点，针对性提高你的阅读水平'])
 
 
 def appears_in_test(word, d):
-    '''
+    """
     如果字符串里没有指定的单词，则返回逗号加单词
     :param word: 指定单词
     :param d: 字符串
     :return: 逗号加单词
-    '''
-    if not word in d:
+    """
+    if word not in d:
         return ''
     else:
         return ','.join(d[word])
@@ -57,10 +58,10 @@ def appears_in_test(word, d):
 
 @app.route("/mark", methods=['GET', 'POST'])
 def mark_word():
-    '''
+    """
     标记单词
     :return: 重定位到主界面
-    '''
+    """
     if request.method == 'POST':
         d = load_freq_history(path_prefix + 'static/frequency/frequency.p')
         lst_history = pickle_idea.dict_to_lst(d)
@@ -70,16 +71,16 @@ def mark_word():
         d = pickle_idea.merge_frequency(lst, lst_history)
         pickle_idea.save_frequency_to_pickle(d, path_prefix + 'static/frequency/frequency.p')
         return redirect(url_for('mainpage'))
-    else: # 不回应GET请求
+    else:  # 不回应GET请求
         return 'Under construction'
 
 
 @app.route("/", methods=['GET', 'POST'])
 def mainpage():
-    '''
+    """
     根据GET或POST方法来返回不同的主界面
     :return: 主界面
-    '''
+    """
     if request.method == 'POST':  # when we submit a form
         content = escape(request.form['content'])
         f = WordFreq(content)
diff --git a/app/pickle_idea.py b/app/pickle_idea.py
index 4f193ff..3e87796 100644
--- a/app/pickle_idea.py
+++ b/app/pickle_idea.py
@@ -11,15 +11,15 @@ from datetime import datetime
 
 
 def lst_to_dict(lst, d):
-    ''' 
+    """
     Store the information in list lst to dictionary d. 
     Note: nothing is returned.
 
-    '''
+    """
     for x in lst:
         word = x[0]
         freq = x[1]
-        if not word in d:
+        if word not in d:
             d[word] = freq 
         else:
             d[word] += freq
@@ -73,15 +73,15 @@ def familiar(path, word):
     fp = open(path, "wb")
     pickle.dump(dic, fp)
 
+
 if __name__ == '__main__':
 
-    lst1 = [('apple',2),  ('banana',1)]
+    lst1 = [('apple', 2),  ('banana', 1)]
     d = {}
-    lst_to_dict(lst1, d) # d will change
-    save_frequency_to_pickle(d, 'frequency.p') # frequency.p is our database
+    lst_to_dict(lst1, d)  # d will change
+    save_frequency_to_pickle(d, 'frequency.p')  # frequency.p is our database
 
-
-    lst2 = [('banana',2), ('orange', 4)]
+    lst2 = [('banana', 2), ('orange', 4)]
     d = load_record('frequency.p')
     lst1 = dict_to_lst(d)
     d = merge_frequency(lst2, lst1)
diff --git a/app/pickle_idea2.py b/app/pickle_idea2.py
index f3104a5..3771bae 100644
--- a/app/pickle_idea2.py
+++ b/app/pickle_idea2.py
@@ -12,22 +12,22 @@ import pickle
 from datetime import datetime
 
 
-def lst2dict(lst, d):
-    ''' 
+def lst_to_dict(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:
+        if word not in d:
             d[word] = dates
         else:
             d[word] += dates
 
 
-def deleteRecord(path, word):
+def delete_record(path, word):
     with open(path, 'rb') as f:
         db = pickle.load(f)
     try:
@@ -35,9 +35,10 @@ def deleteRecord(path, word):
     except KeyError:
         print("sorry")
     with open(path, 'wb') as ff:
-            pickle.dump(db, ff)
+        pickle.dump(db, ff)
 
-def dict2lst(d):
+
+def dict_to_lst(d):
     if len(d) > 0:
         keys = list(d.keys())
         if isinstance(d[keys[0]], int):
@@ -46,14 +47,15 @@ def dict2lst(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 list(d.items())  # a list of (key, value) pairs
 
     return []
 
+
 def merge_frequency(lst1, lst2):
     d = {}
-    lst2dict(lst1, d)
-    lst2dict(lst2, d)
+    lst_to_dict(lst1, d)
+    lst_to_dict(lst2, d)
     return d
 
 
@@ -69,23 +71,22 @@ def save_frequency_to_pickle(d, pickle_fname):
     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])))
+        if k not 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'])]
+    lst1 = [('apple',['201910251437', '201910251438']),  ('banana', ['201910251439'])]
     d = {}
-    lst2dict(lst1, d) # d will change
+    lst_to_dict(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)
+    lst1 = dict_to_lst(d)
     d = merge_frequency(lst2, lst1)
     print(d)
diff --git a/app/user_service.py b/app/user_service.py
index 75971a6..a480247 100644
--- a/app/user_service.py
+++ b/app/user_service.py
@@ -21,6 +21,7 @@ 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)
@@ -42,13 +43,14 @@ def get_next_article(username):
         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=''
+        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
@@ -58,19 +60,20 @@ def get_pre_article(username):
             data = {
                 'visited_articles': visited_articles,
                 'today_article': today_article,
-                'result_of_generate_article':result_of_generate_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)
+    """
+    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
@@ -79,13 +82,13 @@ def unfamiliar(username, word):
 
 @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)
+    """
+    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
@@ -94,14 +97,14 @@ def familiar(username, word):
 
 @userService.route("/<username>/<word>/del", methods=['GET', 'POST'])
 def delete_word(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)
+    pickle_idea2.delete_record(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"
@@ -109,11 +112,11 @@ def delete_word(username, word):
 
 @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')
@@ -136,7 +139,7 @@ def userpage(username):
 
     elif request.method == 'GET':  # when we load a html page
         d = load_freq_history(user_freq_record)
-        lst = pickle_idea2.dict2lst(d)
+        lst = pickle_idea2.dict_to_lst(d)
         lst2 = []
         for t in lst:
             lst2.append((t[0], len(t[1])))
@@ -159,19 +162,20 @@ def userpage(username):
                                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)
+    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_history = pickle_idea2.dict_to_lst(d)
         lst = []
         for word in request.form.getlist('marked'):
             lst.append((word, [get_time()]))
@@ -183,9 +187,9 @@ def user_mark_word(username):
 
 
 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
 
diff --git a/app/wordfreqCMD.py b/app/wordfreqCMD.py
index 69065d6..53ea7f8 100644
--- a/app/wordfreqCMD.py
+++ b/app/wordfreqCMD.py
@@ -11,12 +11,12 @@ import pickle_idea
 
 
 def freq(s):
-    '''
+    """
     功能： 把字符串转成列表。 目的是得到每个单词的频率。
     输入： 字符串
     输出： 列表， 列表里包含一组元组，每个元组包含单词与单词的频率。 比如 [('apple', 2), ('banana', 1)]
     注意事项： 首先要把字符串转成小写。原因是。。。
-    '''
+    """
 
     result = []
     s = s.lower()  # 字母转小写
@@ -71,9 +71,9 @@ def sort_in_ascending_order(lst):  # 单词按频率降序排列
 
 
 def make_html_page(lst, fname):  # 只是在wordfreqCMD.py中的main函数中调用，所以不做修改
-    '''
+    """
     功能：把lst的信息存到fname中，以html格式。
-    '''
+    """
     s = ''
     count = 1
     for x in lst: