diff --git a/app/difficulty.py b/app/difficulty.py
index cb93768..20f947d 100644
--- a/app/difficulty.py
+++ b/app/difficulty.py
@@ -7,6 +7,8 @@
 
 import pickle
 import math
+import time
+
 from wordfreqCMD import remove_punctuation, freq, sort_in_descending_order, sort_in_ascending_order
 import snowballstemmer
 
@@ -24,6 +26,7 @@ def convert_test_type_to_difficulty_level(d):
     :param d: 存储了单词库pickle文件中的单词的字典
     :return:
     """
+    time_start = time.time()
     result = {}
     L = list(d.keys())  # in d, we have test types (e.g., CET4,CET6,BBC) for each word
 
@@ -38,6 +41,8 @@ def convert_test_type_to_difficulty_level(d):
             result[k] = 7
         elif 'BBC' in d[k]:
             result[k] = 8
+    time_end = time.time()
+    print('convert_test_type_to_difficulty_level totally cost', time_end - time_start)
 
     return result  # {'apple': 4, ...}
 
@@ -48,6 +53,7 @@ def get_difficulty_level_for_user(d1, d2):
     d1 用户不会的词
     在d2的后面添加单词，没有新建一个新的字典
     """
+    time_start = time.time()
     # TODO: convert_test_type_to_difficulty_level() should not be called every time.  Each word's difficulty level should be pre-computed.
     d2 = convert_test_type_to_difficulty_level(d2)  # 根据d2的标记评级{'apple': 4, 'abandon': 4, ...}
     stemmer = snowballstemmer.stemmer('english')
@@ -61,6 +67,8 @@ def get_difficulty_level_for_user(d1, d2):
                 d2[k] = d2[stem]  # 按照词根进行评级
             else:
                 d2[k] = 3  # 如果k的词根都不在，那么就当认为是3级
+    time_end = time.time()
+    print('get_difficulty_level_for_user totally cost', time_end - time_start)
     return d2