diff --git a/app/Article.py b/app/Article.py
index df9ac3a..d5e63cd 100644
--- a/app/Article.py
+++ b/app/Article.py
@@ -22,12 +22,12 @@ def total_number_of_essays():
     return len(result)
 
 
-def get_article_title(s):
-    return s.split('\n')[0]
+def get_article_title(article):
+    return article.split('\n')[0]
 
 
-def get_article_body(s):
-    lst = s.split('\n')
+def get_article_body(article):
+    lst = article.split('\n')
     lst.pop(0)  # remove the first line
     return '\n'.join(lst)
 
@@ -111,11 +111,11 @@ def within_range(x, y, r):
     return x > y and abs(x - y) <= r
 
 
-def get_question_part(s):
-    s = s.strip()
+def get_question_part(article):
+    article = article.strip()
     result = []
     flag = 0
-    for line in s.split('\n'):
+    for line in article.split('\n'):
         line = line.strip()
         if line == 'QUESTION':
             result.append(line)
@@ -127,11 +127,11 @@ def get_question_part(s):
     return '\n'.join(result)
 
 
-def get_answer_part(s):
-    s = s.strip()
+def get_answer_part(article):
+    article = article.strip()
     result = []
     flag = 0
-    for line in s.split('\n'):
+    for line in article.split('\n'):
         line = line.strip()
         if line == 'ANSWER':
             flag = 1
diff --git a/app/Login.py b/app/Login.py
index cd750d1..d3d609e 100644
--- a/app/Login.py
+++ b/app/Login.py
@@ -3,23 +3,26 @@ import string
 from datetime import datetime, timedelta
 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()
 
+
 # import model.user after the defination of md5(s) to avoid circular import
 from model.user import get_user_by_username, insert_user, update_password_by_username
 
 path_prefix = '/var/www/wordfreq/wordfreq/'
 path_prefix = './'  # comment this line in deployment
 
-def verify_pass(newpass,oldpass):
-    if(newpass==oldpass):
+
+def verify_pass(new_password, old_password):
+    if new_password == old_password:
         return True
 
 
@@ -43,17 +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
@@ -66,6 +69,7 @@ def get_expiry_date(username):
     else:
         return user.expiry_date
 
+
 class UserName:
     def __init__(self, username):
         self.username = username
@@ -73,11 +77,11 @@ class UserName:
     def validate(self):
         if len(self.username) > 20:
             return f'{self.username} is too long.  The user name cannot exceed 20 characters.'
-        if self.username.startswith('.'): # a user name must not start with a dot
+        if self.username.startswith('.'):  # a user name must not start with a dot
             return 'Period (.) is not allowed as the first letter in the user name.'
-        if ' ' in self.username: # a user name must not include a whitespace
+        if ' ' in self.username:  # a user name must not include a whitespace
             return 'Whitespace is not allowed in the user name.'
-        for c in self.username: # a user name must not include special characters, except non-leading periods or underscores
+        for c in self.username:  # a user name must not include special characters, except non-leading periods or underscores
             if c in string.punctuation and c != '.' and c != '_':
                 return f'{c} is not allowed in the user name.'
         if self.username in ['signup', 'login', 'logout', 'reset', 'mark', 'back', 'unfamiliar', 'familiar', 'del', 'admin']:
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 a7ed0c4..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'})
@@ -43,13 +43,12 @@ def signup():
                 return jsonify({'status': '1'})
 
 
-
 @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')
@@ -74,10 +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'))
@@ -85,10 +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')
@@ -102,9 +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 cb93768..d500cca 100644
--- a/app/difficulty.py
+++ b/app/difficulty.py
@@ -18,25 +18,25 @@ def load_record(pickle_fname):
     return d
 
 
-def convert_test_type_to_difficulty_level(d):
+def convert_test_type_to_difficulty_level(words_dict):
     """
     对原本的单词库中的单词进行难度评级
-    :param d: 存储了单词库pickle文件中的单词的字典
+    :param words_dict: 存储了单词库pickle文件中的单词的字典
     :return:
     """
     result = {}
-    L = list(d.keys())  # in d, we have test types (e.g., CET4,CET6,BBC) for each word
+    words_lst = list(words_dict.keys())  # in words_dict, we have test types (e.g., CET4,CET6,BBC) for each word
 
-    for k in L:
-        if 'CET4' in d[k]:
+    for k in words_lst:
+        if 'CET4' in words_dict[k]:
             result[k] = 4  # CET4 word has level 4
-        elif 'OXFORD3000' in d[k]:
+        elif 'OXFORD3000' in words_dict[k]:
             result[k] = 5
-        elif 'CET6' in d[k] or 'GRADUATE' in d[k]:
+        elif 'CET6' in words_dict[k] or 'GRADUATE' in words_dict[k]:
             result[k] = 6
-        elif 'OXFORD5000' in d[k] or 'IELTS' in d[k]:
+        elif 'OXFORD5000' in words_dict[k] or 'IELTS' in words_dict[k]:
             result[k] = 7
-        elif 'BBC' in d[k]:
+        elif 'BBC' in words_dict[k]:
             result[k] = 8
 
     return result  # {'apple': 4, ...}
@@ -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 4e3f829..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])
@@ -57,36 +58,36 @@ 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.dict2lst(d)
+        lst_history = pickle_idea.dict_to_lst(d)
         lst = []
         for word in request.form.getlist('marked'):
             lst.append((word, 1))
         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)
         lst = f.get_freq()
         # save history
         d = load_freq_history(path_prefix + 'static/frequency/frequency.p')
-        lst_history = pickle_idea.dict2lst(d)
+        lst_history = pickle_idea.dict_to_lst(d)
         d = pickle_idea.merge_frequency(lst, lst_history)
         pickle_idea.save_frequency_to_pickle(d, path_prefix + 'static/frequency/frequency.p')
         return render_template('mainpage_post.html', lst=lst, yml=Yaml.yml)
@@ -96,8 +97,8 @@ def mainpage():
         number_of_essays = total_number_of_essays()
         d = load_freq_history(path_prefix + 'static/frequency/frequency.p')
         d_len = len(d)
-        lst = sort_in_descending_order(pickle_idea.dict2lst(d))
-        return render_template('mainpage_get.html', 
+        lst = sort_in_descending_order(pickle_idea.dict_to_lst(d))
+        return render_template('mainpage_get.html',
                                admin_name=ADMIN_NAME,
                                random_ads=random_ads,
                                d_len=d_len,
diff --git a/app/pickle_idea.py b/app/pickle_idea.py
index 45bd19a..3e87796 100644
--- a/app/pickle_idea.py
+++ b/app/pickle_idea.py
@@ -10,29 +10,29 @@ 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]
         freq = x[1]
-        if not word in d:
+        if word not in d:
             d[word] = freq 
         else:
             d[word] += freq
 
 
-def dict2lst(d):
-    return list(d.items()) # a list of (key, value) pairs
+def dict_to_lst(d):
+    return list(d.items())  # a list of (key, value) pairs
         
 
-def merge_frequency(lst1, lst2):
+def merge_frequency(list1, list2):
     d = {}
-    lst2dict(lst1, d)
-    lst2dict(lst2, d)
+    lst_to_dict(list1, d)
+    lst_to_dict(list2, d)
     return d
 
 
@@ -54,33 +54,35 @@ def save_frequency_to_pickle(d, pickle_fname):
     pickle.dump(d2, f)
     f.close()
 
-def unfamiliar(path,word):
-    f = open(path,"rb")
+
+def unfamiliar(path, word):
+    f = open(path, "rb")
     dic = pickle.load(f)
     dic[word] += [datetime.now().strftime('%Y%m%d%H%M')]
-    fp = open(path,"wb")
-    pickle.dump(dic,fp)
+    fp = open(path, "wb")
+    pickle.dump(dic, fp)
 
-def familiar(path,word):
-    f = open(path,"rb")
+
+def familiar(path, word):
+    f = open(path, "rb")
     dic = pickle.load(f)
-    if len(dic[word])>1:
+    if len(dic[word]) > 1:
         del dic[word][0]
     else:
         dic.pop(word)
-    fp = open(path,"wb")
-    pickle.dump(dic,fp)
+    fp = open(path, "wb")
+    pickle.dump(dic, fp)
+
 
 if __name__ == '__main__':
 
-    lst1 = [('apple',2),  ('banana',1)]
+    lst1 = [('apple', 2),  ('banana', 1)]
     d = {}
-    lst2dict(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 = dict2lst(d)
+    lst1 = dict_to_lst(d)
     d = merge_frequency(lst2, lst1)
     print(d)
diff --git a/app/pickle_idea2.py b/app/pickle_idea2.py
index 0da55bc..3771bae 100644
--- a/app/pickle_idea2.py
+++ b/app/pickle_idea2.py
@@ -11,21 +11,23 @@
 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:
@@ -33,9 +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):
@@ -44,14 +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
 
 
@@ -67,23 +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 2e5feed..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
@@ -93,15 +96,15 @@ def familiar(username, word):
 
 
 @userService.route("/<username>/<word>/del", methods=['GET', 'POST'])
-def deleteword(username, word):
-    '''
+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 deleteword(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()]))
@@ -181,10 +185,11 @@ def user_mark_word(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
 
diff --git a/app/wordfreqCMD.py b/app/wordfreqCMD.py
index e56ba0c..53ea7f8 100644
--- a/app/wordfreqCMD.py
+++ b/app/wordfreqCMD.py
@@ -6,74 +6,74 @@
 import collections
 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。
+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。
 import pickle_idea
 
-def freq(fruit):
-    '''
+
+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 = []
-    
-    fruit = fruit.lower() # 字母转小写
-    flst = fruit.split()  # 字符串转成list
-    c = collections.Counter(flst)
+    s = s.lower()  # 字母转小写
+    word_lst = s.split()  # 字符串转成list
+    c = collections.Counter(word_lst)
     result = c.most_common()
     return result
 
 
-def youdao_link(s): # 有道链接
-    link = 'http://youdao.com/w/eng/' + s + '/#keyfrom=dict2.index'# 网址
+def youdao_link(word):  # 有道链接
+    link = 'http://youdao.com/w/eng/' + word + '/#keyfrom=dict2.index'  # 网址
     return link
 
 
-def file2str(fname):#文件转字符
-    f = open(fname) #打开
-    s = f.read()    #读取
-    f.close()       #关闭
-    return s
+def file_to_str(f_name):  # 文件转字符
+    f = open(f_name)  # 打开
+    f_str = f.read()  # 读取
+    f.close()  # 关闭
+    return f_str
 
 
-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 = '\_©~<=>+-/[]*&$%^@.,?!:;#()"“”—‘’{}|' # 把里面的字符都去掉
+def remove_punctuation(s):  # 这里是words_text是形参 (parameter)。函数被调用时才给words_text赋值。
+    special_characters = '\_©~<=>+-/[]*&$%^@.,?!:;#()"“”—‘’{}|'  # 把里面的字符都去掉
     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(c, ' ')  # 防止出现把 apple,apple 移掉逗号后变成 appleapple 情况
     s = s.replace('--', ' ')
-    s = s.strip() # 去除前后的空格
-    
+    s = s.strip()  # 去除前后的空格
+
     if '\'' in s:
         n = len(s)
-        t = '' # 用来收集我需要保留的字符
-        for i in range(n): # 只有单引号前后都有英文字符，才保留
+        characters = ''  # 用来收集我需要保留的字符
+        for i in range(n):  # 只有单引号前后都有英文字符，才保留
             if s[i] == '\'':
                 i_is_ok = i - 1 >= 0 and i + 1 < n
-                if i_is_ok and s[i-1] in string.ascii_letters and s[i+1] in string.ascii_letters:
-                    t += s[i]
+                if i_is_ok and s[i - 1] in string.ascii_letters and s[i + 1] in string.ascii_letters:
+                    characters += s[i]
             else:
-                t += s[i]
-        return t
+                characters += s[i]
+        return characters
     else:
         return s
 
 
-def sort_in_descending_order(lst):# 单词按频率降序排列
+def sort_in_descending_order(lst):  # 单词按频率降序排列
     lst2 = sorted(lst, reverse=True, key=lambda x: (x[1], x[0]))
     return lst2
 
 
-def sort_in_ascending_order(lst):# 单词按频率降序排列
+def sort_in_ascending_order(lst):  # 单词按频率降序排列
     lst2 = sorted(lst, reverse=False, key=lambda x: (x[1], x[0]))
     return lst2
 
 
 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:
@@ -89,22 +89,22 @@ def make_html_page(lst, fname):  # 只是在wordfreqCMD.py中的main函数中调
 if __name__ == '__main__':
     num = len(sys.argv)
 
-    if num == 1: # 从键盘读入字符串
+    if num == 1:  # 从键盘读入字符串
         s = input()
-    elif num == 2: # 从文件读入字符串
+    elif num == 2:  # 从文件读入字符串
         fname = sys.argv[1]
-        s = file2str(fname)
+        s = file_to_str(fname)
     else:
         print('I can accept at most 2 arguments.')
-        sys.exit()# 结束程序运行， 下面的代码不会被执行了。
+        sys.exit()  # 结束程序运行， 下面的代码不会被执行了。
 
-    s = remove_punctuation(s) # 这里是s是实参(argument)，里面有值
+    s = remove_punctuation(s)  # 这里是s是实参(argument)，里面有值
     L = freq(s)
     for x in sort_in_descending_order(L):
-        print('%s\t%d\t%s' % (x[0], x[1], youdao_link(x[0])))#函数导出
+        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'):
@@ -112,12 +112,9 @@ if __name__ == '__main__':
     else:
         d = {}
 
-    print(sort_in_descending_order(pickle_idea.dict2lst(d)))
+    print(sort_in_descending_order(pickle_idea.dict_to_lst(d)))
 
     # 合并频率
-    lst_history = pickle_idea.dict2lst(d)
+    lst_history = pickle_idea.dict_to_lst(d)
     d = pickle_idea.merge_frequency(L, lst_history)
     pickle_idea.save_frequency_to_pickle(d, 'frequency.p')
-
-
-
diff --git a/requirements.txt b/requirements.txt
index 338b71c..2210969 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-Flask==1.1.2
+Flask==2.2.3
 selenium==3.141.0
 PyYAML~=6.0
 pony==0.7.16