diff --git a/app/Article.py b/app/Article.py
index 6281c38..e0f006a 100644
--- a/app/Article.py
+++ b/app/Article.py
@@ -35,11 +35,14 @@ def get_article_body(s):
 def get_today_article(user_word_list, existing_articles):
     rq = RecordQuery(path_prefix + 'static/wordfreqapp.db')
     if existing_articles is None:
-        existing_articles = [0, []]  # existing_articles[0]：为existing_articles[1]的索引；existing_articles[1]:之前显示文章的id列表，越后越新
-    if existing_articles[0] > len(existing_articles[1])-1:
+        existing_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 existing_articles["index"] > len(existing_articles["article_ids"])-1:
         rq.instructions("SELECT * FROM article")
     else:
-        rq.instructions('SELECT * FROM article WHERE article_id=%d' % (existing_articles[1][existing_articles[0]]))
+        rq.instructions('SELECT * FROM article WHERE article_id=%d' % (existing_articles["article_ids"][existing_articles["index"]]))
     rq.do()
     result = rq.get_results()
     random.shuffle(result)
@@ -49,28 +52,29 @@ def get_today_article(user_word_list, existing_articles):
     d2 = load_freq_history(path_prefix + 'static/words_and_tests.p')
     d3 = get_difficulty_level(d1, d2)
 
-    d = {}
+    d = None
     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.
     text_level = 0
-    flag = False
-    if existing_articles[0] > len(existing_articles[1])-1:  # 下一篇
+    if existing_articles["index"] > len(existing_articles["article_ids"])-1:  # 下一篇
+        flag_get_article = False
         for reading in result:
             text_level = text_difficulty_level(reading['text'], d3)
             factor = random.gauss(0.8,
                                   0.1)  # a number drawn from Gaussian distribution with a mean of 0.8 and a stand deviation of 1
-            if reading['article_id'] not in existing_articles[1] and within_range(text_level, user_level, (8.0 - user_level) * factor):  # 新的文章之前没有出现过且符合一定范围的水平
+            if reading['article_id'] not in existing_articles["article_ids"] and within_range(text_level, user_level, (8.0 - user_level) * factor):  # 新的文章之前没有出现过且符合一定范围的水平
                 d = reading
-                existing_articles[1].append(d['article_id'])  # 列表添加新的文章id；下面进行
-                flag = True
+                existing_articles["article_ids"].append(d['article_id'])  # 列表添加新的文章id；下面进行
+                flag_get_article = True
                 break
+        if not flag_get_article:
+            existing_articles["index"] -= 1
     else:  # 上一篇
         d = random.choice(result)
         text_level = text_difficulty_level(d['text'], d3)
-        flag = True
 
     today_article = None
-    if flag:
+    if d:
         today_article = {
             "user_level": '%4.2f' % user_level,
             "text_level": '%4.2f' % text_level,
@@ -81,8 +85,6 @@ def get_today_article(user_word_list, existing_articles):
             "question": get_question_part(d['question']),
             "answer": get_answer_part(d['question'])
         }
-    else:
-        existing_articles[0] -= 1
 
     return existing_articles, today_article
 
diff --git a/app/templates/userpage_get.html b/app/templates/userpage_get.html
index c9a04c1..298b559 100644
--- a/app/templates/userpage_get.html
+++ b/app/templates/userpage_get.html
@@ -45,7 +45,7 @@
 {#    {% endfor %}#}
 
     <a class="btn btn-success" href="/{{ username }}/reset" role="button"> 下一篇 Next Article </a>
-    {% if session.get('existing_articles')[0] != None and session.get('existing_articles')[0] !=0 %}
+    {% if session.get('existing_articles') != None and session.get('existing_articles')["index"] !=0 %}
         <a class="btn btn-success" href="/{{ username }}/back" role="button"> 上一篇 Previous Article </a>
     {% endif %}
 
diff --git a/app/user_service.py b/app/user_service.py
index 1b47d74..8d1dbfc 100644
--- a/app/user_service.py
+++ b/app/user_service.py
@@ -31,7 +31,7 @@ def user_reset(username):
     '''
     if request.method == 'GET':
         existing_articles = session.get("existing_articles")
-        existing_articles[0] += 1
+        existing_articles["index"] += 1
         session["existing_articles"] = existing_articles
         return redirect(url_for('user_bp.userpage', username=username))
     else:
@@ -46,7 +46,7 @@ def user_back(username):
     '''
     if request.method == 'GET':
         existing_articles = session.get("existing_articles")
-        existing_articles[0] -= 1
+        existing_articles["index"] -= 1
         session["existing_articles"] = existing_articles
         return redirect(url_for('user_bp.userpage', username=username))