diff --git a/app/Article.py b/app/Article.py
index 7f41b1e..774d25a 100644
--- a/app/Article.py
+++ b/app/Article.py
@@ -49,8 +49,7 @@ def get_today_article(user_word_list, articleID):
 
     d = {}
     d_user = load_freq_history(user_word_list)
-    user_level = user_difficulty_level(d_user,
-                                       d3)  # more consideration as user's behaviour is dynamic. Time factor should be considered.
+    user_level = user_difficulty_level(d_user, d3)  # more consideration as user's behaviour is dynamic. Time factor should be considered.
     random.shuffle(result)  # shuffle list
     d = random.choice(result)
     text_level = text_difficulty_level(d['text'], d3)
@@ -128,7 +127,7 @@ def get_answer_part(s):
        else
           e.style.display = 'block';
     }
-</script>   
+</script>
     '''
     html_code = js
     html_code += '\n'
diff --git a/app/Login.py b/app/Login.py
index c06a1b2..65047f7 100644
--- a/app/Login.py
+++ b/app/Login.py
@@ -1,6 +1,5 @@
 import hashlib
 from datetime import datetime
-
 from UseSqlite import InsertQuery, RecordQuery
 
 path_prefix = '/var/www/wordfreq/wordfreq/'
@@ -10,7 +9,8 @@ path_prefix = './'  # comment this line in deployment
 def verify_user(username, password):
     rq = RecordQuery(path_prefix + 'static/wordfreqapp.db')
     password = md5(username + password)
-    rq.instructions_with_parameters("SELECT * FROM user WHERE name=? AND password=?", (username, password))
+    rq.instructions_with_parameters("SELECT * FROM user WHERE name=:username AND password=:password", dict(
+        username=username, password=password))  # the named style https://docs.python.org/3/library/sqlite3.html
     rq.do_with_parameters()
     result = rq.get_results()
     return result != []
@@ -22,14 +22,16 @@ def add_user(username, password):
     # 将用户名和密码一起加密，以免暴露不同用户的相同密码
     password = md5(username + password)
     rq = InsertQuery(path_prefix + 'static/wordfreqapp.db')
-    rq.instructions("INSERT INTO user VALUES ('%s', '%s', '%s', '%s')" % (username, password, start_date, expiry_date))
-    rq.do()
+    rq.instructions_with_parameters("INSERT INTO user VALUES (:username, :password, :start_date, :expiry_date)", dict(
+        username=username, password=password, start_date=start_date, expiry_date=expiry_date))
+    rq.do_with_parameters()
 
 
 def check_username_availability(username):
     rq = RecordQuery(path_prefix + 'static/wordfreqapp.db')
-    rq.instructions("SELECT * FROM user WHERE name='%s'" % (username))
-    rq.do()
+    rq.instructions_with_parameters(
+        "SELECT * FROM user WHERE name=:username", dict(username=username))
+    rq.do_with_parameters()
     result = rq.get_results()
     return result == []
 
@@ -47,15 +49,17 @@ def change_password(username, old_password, new_password):
     # 将用户名和密码一起加密，以免暴露不同用户的相同密码
     password = md5(username + new_password)
     rq = InsertQuery(path_prefix + 'static/wordfreqapp.db')
-    rq.instructions("UPDATE user SET password = '%s' WHERE name = '%s'" % (password, username))
-    rq.do()
+    rq.instructions_with_parameters("UPDATE user SET password=:password WHERE name=:username", dict(
+        password=password, username=username))
+    rq.do_with_parameters()
     return True
 
 
 def get_expiry_date(username):
     rq = RecordQuery(path_prefix + 'static/wordfreqapp.db')
-    rq.instructions("SELECT expiry_date FROM user WHERE name='%s'" % (username))
-    rq.do()
+    rq.instructions_with_parameters(
+        "SELECT expiry_date FROM user WHERE name=:username", dict(username=username))
+    rq.do_with_parameters()
     result = rq.get_results()
     if len(result) > 0:
         return result[0]['expiry_date']
@@ -70,4 +74,4 @@ def md5(s):
     :return: 经MD5以后的字符串
     '''
     h = hashlib.md5(s.encode(encoding='utf-8'))
-    return h.hexdigest()
\ No newline at end of file
+    return h.hexdigest()
diff --git a/app/UseSqlite.py b/app/UseSqlite.py
index 660710f..ea4baeb 100644
--- a/app/UseSqlite.py
+++ b/app/UseSqlite.py
@@ -12,26 +12,26 @@ 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()  
-    
+        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
@@ -46,11 +46,11 @@ class Sqlite3Template:
         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):
@@ -64,23 +64,23 @@ class RecordQuery(Sqlite3Template):
                 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()
diff --git a/app/account_service.py b/app/account_service.py
index 3f5cf60..753c51e 100644
--- a/app/account_service.py
+++ b/app/account_service.py
@@ -17,8 +17,8 @@ def signup():
         return render_template('signup.html')
     elif request.method == 'POST':
         # 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 = request.form['username']
-        password = request.form['password']
+        username = escape(request.form['username'])
+        password = escape(request.form['password'])
 
         available = check_username_availability(username)
         if not available: # 用户名不可用
@@ -60,8 +60,8 @@ def login():
     elif request.method == 'POST':
         # POST方法用于判断登录是否成功
         # check database and verify user
-        username = request.form['username']
-        password = request.form['password']
+        username = escape(request.form['username'])
+        password = escape(request.form['password'])
         verified = verify_user(username, password)
         if verified:
             # 登录成功，写入session
@@ -104,15 +104,15 @@ def reset():
         return render_template('reset.html', username=session['username'], state='wait')
     else:
         # POST请求用于提交修改后信息
-        old_psd = request.form['old-psd']
-        new_psd = request.form['new-psd']
-        flag = change_password(username, old_psd, new_psd) # flag表示是否修改成功
+        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
         if flag:
             session['logged_in'] = False
             return \
 '''
 <script>
-alert('修改密码成功!!!请重新登录');
+alert('密码修改成功，请重新登录。');
 window.location.href="/login";
 </script>
 
@@ -122,7 +122,7 @@ window.location.href="/login";
             return \
 '''
 <script>
-alert('修改密码失败!!!');
+alert('密码修改失败');
 window.location.href="/reset";
 </script>
 
diff --git a/app/templates/mainpage_get.html b/app/templates/mainpage_get.html
index 6e1d9b4..4e69243 100644
--- a/app/templates/mainpage_get.html
+++ b/app/templates/mainpage_get.html
@@ -25,7 +25,7 @@
         {% if session['logged_in'] %}
             <a href="/{{session['username']}}">{{session['username']}}</a></p>
         {% else %}
-            <p><a href="/login">登录</a>  <a href="/signup">成为会员</a> <a href="/static/usr/instructions.html">使用说明</a></p >
+            <p><a href="/login">登录</a>  <a href="/signup">注册</a> <a href="/static/usr/instructions.html">使用说明</a></p >
             <p><b>{{random_ads|safe}}</b></p>
         {% endif %}
         <div class="alert alert-success" role="alert">共有文章 <span class="badge bg-success"> {{number_of_essays}} </span> 篇</div>
diff --git a/app/templates/reset.html b/app/templates/reset.html
index e510d3d..b26de3c 100644
--- a/app/templates/reset.html
+++ b/app/templates/reset.html
@@ -2,10 +2,10 @@
     <body>
     <form action="/reset" method='POST'>
         旧密码:
-        <input type="password" name="old-psd" />
+        <input type="password" name="old-password" />
         <br/>
         新密码:
-        <input type="password" name="new-psd" />
+        <input type="password" name="new-password" />
         <br/>
         <input type="submit" name="submit" value="提交" />
         <input type="button" name="submit" value="放弃修改" onclick="window.location.href='/{{ username }}'"/>