diff --git a/app/helpers/exercises_helper.rb b/app/helpers/exercises_helper.rb
index 4530167ba..856f808d7 100644
--- a/app/helpers/exercises_helper.rb
+++ b/app/helpers/exercises_helper.rb
@@ -355,9 +355,9 @@ module ExercisesHelper
     exercise_questions = exercise.exercise_questions.includes(:exercise_answers,:exercise_shixun_answers,:exercise_standard_answers,:exercise_shixun_challenges)
     exercise_questions.each do |q|
       if q.question_type != 5
-        answers_content = q.exercise_answers.search_answer_users("user_id",user.id)  #学生的答案
+        answers_content = q.exercise_answers.where(user_id: user.id)  #学生的答案
       else
-        answers_content = q.exercise_shixun_answers.search_shixun_answers("user_id",user.id)  #学生的答案
+        answers_content = q.exercise_shixun_answers.where(user_id: user.id)  #学生的答案
       end
       if q.question_type <= 2  #为选择题或判断题时
         if answers_content.present?   #学生有回答时
@@ -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
-              q_score_1 = (q.question_score / standard_answer.count)   #当多选答案正确时，每个answer的分数均摊。
+              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。
             else
-              q_score_1 = 0.0
+              multi_each_score = 0.0
             end
-            answers_content.update_all(:score => q_score_1)
+            answers_content.update_all(:score => multi_each_score)
             score1 = score1 + q.question_score
           end
         else
@@ -424,7 +424,7 @@ module ExercisesHelper
             end
             ex_shixun_answer_content = answers_content&.where(exercise_shixun_challenge_id: exercise_cha.id)
             if ex_shixun_answer_content.blank?  #把关卡的答案存入试卷的实训里
-              cha_path = challenge_path exercise_cha.challenge&.path
+              cha_path = challenge_path(exercise_cha.challenge&.path)
               game_challenge = game.game_codes.search_challenge_path(cha_path)&.first
               if game_challenge.present?
                 game_code = game_challenge
@@ -682,16 +682,26 @@ module ExercisesHelper
   def get_exercise_left_time(exercise,user)
     ex_time = exercise.time
     user_left_time = nil
+    time_now_i = Time.now.to_i
     if ex_time > 0
       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
-      if (exercise_user_start + time_mill) > exercise_end_time
-        time_mill = exercise_end_time - exercise_user_start   #如果开始答题时间加试卷的限时长大于试卷的截止时间，则以试卷的截止时间到开始答题时间为试卷的限时
+      #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
+          user_left_time = time_mill
+        else
+          user_left_time = (exercise_end_time < time_now_i) ? nil : (exercise_end_time - time_now_i)
+        end
+      else
+        if (exercise_user_start + time_mill) > exercise_end_time
+          time_mill = exercise_end_time - exercise_user_start   #如果开始答题时间加试卷的限时长大于试卷的截止时间，则以试卷的截止时间到开始答题时间为试卷的限时
+        end
+        exercise_user_left_time = time_now_i - exercise_user_start   #用户已回答的时间
+        user_left_time = (time_mill < exercise_user_left_time) ? nil : (time_mill - exercise_user_left_time)   #当前用户对试卷的回答剩余时间
       end
-      exercise_user_left_time = Time.now.to_i - exercise_user_start   #用户已回答的时间
-      user_left_time = (time_mill < exercise_user_left_time) ? nil : (time_mill - exercise_user_left_time)   #当前用户对试卷的回答剩余时间
     end
     user_left_time
   end
diff --git a/app/helpers/export_helper.rb b/app/helpers/export_helper.rb
index af883131a..22c10bdb3 100644
--- a/app/helpers/export_helper.rb
+++ b/app/helpers/export_helper.rb
@@ -89,11 +89,12 @@ module ExportHelper
         if teacher_comments.present?
           w_18 = ""
           teacher_comments.each do |t|
-            user_name = t.user.real_name
+            user_name = t.user&.real_name
             user_time = format_time(t.updated_at)
-            user_score = t.score
-            user_comment = t.comment
-            w_18 = w_18 + ("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")
+            user_score = t&.score
+            user_comment = 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
         else
           w_18 = "--"
@@ -160,11 +161,13 @@ module ExportHelper
         if teacher_comments.present?
           w_18 = ""
           teacher_comments.each do |t|
-            user_name = t.user.real_name
+            user_name = t.user&.real_name
             user_time = format_time(t.updated_at)
-            user_score = t.score
-            user_comment = t.comment
-            w_18 = w_18 + ("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")
+            user_score = t&.score
+            user_comment = 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
           end
         else
           w_18 = "--"
diff --git a/app/tasks/exercise_publish_task.rb b/app/tasks/exercise_publish_task.rb
index 387a834f1..4c8ee39e8 100644
--- a/app/tasks/exercise_publish_task.rb
+++ b/app/tasks/exercise_publish_task.rb
@@ -44,7 +44,7 @@ class ExercisePublishTask
     end
 
     # 分组设置发布时间的测验
-    exercise_group_settings = ExerciseGroupSetting.where("publish_time < ? and publish_time > ?", Time.now + 1800, Time.now - 1800)
+    exercise_group_settings = ExerciseGroupSetting.where("publish_time < ? and publish_time > ?", Time.now + 900, Time.now - 900)
     exercise_group_settings.each do |exercise_group|
       exercise = exercise_group.exercise
       if exercise.present?
@@ -70,12 +70,12 @@ class ExercisePublishTask
     Rails.logger.info("log--------------------------------exercise_end start")
     puts "--------------------------------exercise_end start"
     # 1。统一设置的试卷
-    exercises = Exercise.includes(:exercise_users,:exercise_questions).where("exercise_status = 2 AND unified_setting = true AND end_time <= ?",Time.now)
+    exercises = Exercise.includes(:exercise_users,:exercise_questions).where("exercise_status = 2 AND unified_setting = true AND end_time <= ?",Time.now + 900)
     exercises.each do |exercise|
       ex_type = exercise.exercise_questions.pluck(:question_type).uniq
       exercise.update_column('exercise_status', 3)
       exercise.exercise_users.each do |exercise_user|
-        if exercise_user.commit_status == 0 && exercise_user.start_at.present?
+        if exercise_user&.commit_status == 0 && exercise_user&.start_at.present?
           s_score = calculate_student_score(exercise, exercise_user.user)[:total_score]
           if ex_type.include?(4)   #是否包含主观题
             subjective_score = exercise_user.subjective_score
@@ -98,7 +98,7 @@ class ExercisePublishTask
     end
 
     # 2.非统一的试卷
-    all_exercises = Exercise.includes(:exercise_group_settings,:exercise_users,:exercise_questions).where("unified_setting = false AND exercise_status = 2 AND end_time > ?",Time.now)
+    all_exercises = Exercise.includes(:exercise_group_settings,:exercise_users,:exercise_questions).where("unified_setting = false AND exercise_status = 2 AND end_time > ?",Time.now + 900)
     exercise_ids = all_exercises.blank? ? "(-1)" : "(" + all_exercises.map(&:id).join(",") + ")"
     ex_group_settings = ExerciseGroupSetting.where("end_time <= '#{Time.now}' and exercise_id in #{exercise_ids}")
     ex_group_settings.each do |exercise_setting|
diff --git a/app/templates/exercise_export/exercise_export.css b/app/templates/exercise_export/exercise_export.css
index f5022527e..59be4f1bd 100644
--- a/app/templates/exercise_export/exercise_export.css
+++ b/app/templates/exercise_export/exercise_export.css
@@ -241,7 +241,7 @@ p{
     position: absolute;
     display: inline-block;
     bottom: 9px;
-    left: 1px;
+    left: 2px;
 }
 table{
     width:100%;
diff --git a/app/templates/exercise_export/exercise_user.html.erb b/app/templates/exercise_export/exercise_user.html.erb
index 70c023d26..193a25301 100644
--- a/app/templates/exercise_export/exercise_user.html.erb
+++ b/app/templates/exercise_export/exercise_user.html.erb
@@ -249,8 +249,8 @@
                     <tbody>
                     <% if @games.size > 0 %>
                       <% @games.each_with_index do |game, index| %>
-                        <% user_score = q.exercise_shixun_answers.where(exercise_shixun_challenge_id:game.challenge.id,user_id: @ex_user_user.id) %>
                         <% game_score = q.exercise_shixun_challenges.where(challenge_id:game.challenge.id) %>
+                        <% user_score = q.exercise_shixun_answers.where(exercise_shixun_challenge_id: game_score&.first&.id,user_id: @ex_user_user.id) %>
                         <tr>
                           <td><%= index + 1 %></td>
                           <td style="text-align: left;">