diff --git a/app/helpers/exercises_helper.rb b/app/helpers/exercises_helper.rb
index 856f808d7..604258c32 100644
--- a/app/helpers/exercises_helper.rb
+++ b/app/helpers/exercises_helper.rb
@@ -369,11 +369,11 @@ module ExercisesHelper
           standard_answer = q.exercise_standard_answers.pluck(:exercise_choice_id).sort  #该问题的标准答案，可能有多个
           if user_answer_content == standard_answer  #答案一致,多选或单选才给分，答案不对不给分
             if standard_answer.count > 0
-              multi_each_score = (q.question_score / standard_answer.count)   #当多选答案正确时，每个answer的分数均摊。
+              q_score_1 = (q.question_score.to_f / standard_answer.count)   #当多选答案正确时，每个answer的分数均摊。
             else
-              multi_each_score = 0.0
+              q_score_1 = 0.0
             end
-            answers_content.update_all(:score => multi_each_score)
+            answers_content.update_all(:score => q_score_1)
             score1 = score1 + q.question_score
           end
         else
@@ -461,13 +461,13 @@ module ExercisesHelper
           "q_type":q.question_type,
           "q_position":q.question_number, #该问题的位置
           "stand_status":stand_answer,  #该问题是否正确,1为正确，0为错误
-          "user_score":user_scores  #每个问题的总得分
+          "user_score":user_scores.round(1)  #每个问题的总得分
       }
       ques_stand.push(ques_option)
     end
     total_score = score1 + score2 + score5
     {
-        "total_score":total_score,
+        "total_score":total_score.round(1),
         "stand_status":ques_stand
     }
   end
@@ -687,7 +687,7 @@ module ExercisesHelper
       exercise_user = exercise.exercise_users.find_by(user_id:user.id)
       time_mill = ex_time * 60   #转为秒
       exercise_end_time = exercise.end_time.present? ? exercise.end_time.to_i : 0
-      exercise_user_start = exercise_user.present? ? exercise_user.start_at.to_i : 0
+      exercise_user_start = exercise_user&.start_at.present? ? exercise_user.start_at.to_i : 0
       #用户未开始答题时，即exercise_user_start为0
       if exercise_user_start == 0
         if (exercise_end_time - time_now_i) > time_mill
diff --git a/app/helpers/export_helper.rb b/app/helpers/export_helper.rb
index 22c10bdb3..b6720c66c 100644
--- a/app/helpers/export_helper.rb
+++ b/app/helpers/export_helper.rb
@@ -92,7 +92,7 @@ module ExportHelper
             user_name = t.user&.real_name
             user_time = format_time(t.updated_at)
             user_score = t&.score
-            user_comment = t&.comment
+            user_comment = t.comment.present? ? t.comment : "--"
             comment_title = "教师:#{user_name}\n时间:#{user_time.to_s}\n分数:#{user_score.to_s}分\n评语:#{user_comment}\n\n"
             w_18 = w_18 + comment_title
           end
@@ -164,7 +164,7 @@ module ExportHelper
             user_name = t.user&.real_name
             user_time = format_time(t.updated_at)
             user_score = t&.score
-            user_comment = t&.comment
+            user_comment = t.comment.present? ? t.comment : "--"
             comment_title = "教师:#{user_name}\n时间:#{user_time.to_s}\n分数:#{user_score.to_s}分\n评语:#{user_comment}\n\n"
             # ("教师:" + user_name + "\n" + "时间:" + user_time.to_s + "\n" + "分数:" + user_score.to_s + "分" + "\n" + "评语:" + user_comment + "\n\n")
             w_18 = w_18 + comment_title
diff --git a/app/models/edu_setting.rb b/app/models/edu_setting.rb
index 4b39dea81..835aaec76 100644
--- a/app/models/edu_setting.rb
+++ b/app/models/edu_setting.rb
@@ -20,6 +20,6 @@ class EduSetting < ApplicationRecord
   private
 
   def expire_value_cache
-    Rails.cache.clear(value_cache_key)
+    Rails.cache.write(value_cache_key, value)
   end
 end
diff --git a/app/views/exercises/index.json.jbuilder b/app/views/exercises/index.json.jbuilder
index d7d51c343..4694ecdf0 100644
--- a/app/views/exercises/index.json.jbuilder
+++ b/app/views/exercises/index.json.jbuilder
@@ -23,7 +23,8 @@ if @exercises_count > 0
       ex_index = exercise_index_show(exercise,@course,@is_teacher_or,@current_user_)
       json.extract! exercise, :id, :exercise_name,:is_public,:created_at
       if @is_teacher_or == 2
-        json.time get_exercise_left_time(exercise,@current_user_)
+        second_left = get_exercise_left_time(exercise,@current_user_)
+        json.time second_left.present? ? (second_left / 60) : nil
       end
 
       json.exercise_status ex_index[:ex_status]