diff --git a/server/apps/exam/migrations/0004_auto_20221114_1108.py b/server/apps/exam/migrations/0004_auto_20221114_1108.py
new file mode 100644
index 0000000..a26aad5
--- /dev/null
+++ b/server/apps/exam/migrations/0004_auto_20221114_1108.py
@@ -0,0 +1,18 @@
+# Generated by Django 3.0.5 on 2022-11-14 03:08
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('exam', '0003_auto_20221108_0901'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='examrecord',
+            name='end_time',
+            field=models.DateTimeField(blank=True, null=True, verbose_name='结束答题时间'),
+        ),
+    ]
diff --git a/server/apps/exam/models.py b/server/apps/exam/models.py
index dd35c3f..203f6a9 100644
--- a/server/apps/exam/models.py
+++ b/server/apps/exam/models.py
@@ -108,7 +108,7 @@ class ExamRecord(CommonAModel):
     score = models.FloatField(default=0, verbose_name='得分')
     took = models.IntegerField(default=0, verbose_name='耗时(秒)')
     start_time = models.DateTimeField(verbose_name='开始答题时间')
-    end_time = models.DateTimeField(verbose_name='结束答题时间')
+    end_time = models.DateTimeField(verbose_name='结束答题时间', null=True, blank=True)
     detail = models.ManyToManyField(Question, verbose_name='答题记录', through='AnswerDetail')
     is_pass = models.BooleanField(default=True, verbose_name='是否通过')
     exam = models.ForeignKey(Exam, verbose_name='关联的正式考试', null=True, blank=True, on_delete= models.SET_NULL)
diff --git a/server/apps/exam/serializers.py b/server/apps/exam/serializers.py
index 9313fbf..5c4afbf 100644
--- a/server/apps/exam/serializers.py
+++ b/server/apps/exam/serializers.py
@@ -164,7 +164,7 @@ class AnswerDetailSerializer(ModelSerializer):
     level = serializers.ReadOnlyField(source='question.level')
 
     class Meta:
-        model = PaperQuestion
+        model = AnswerDetail
         fields = ['id', 'question', 'name', 'options', 'right', 'type', 'level',
                   'total_score', 'questioncat_name', 'img', 'user_answer', 'score', 'is_right']
 
@@ -179,6 +179,6 @@ class AnswerDetailOutSerializer(ModelSerializer):
     level = serializers.ReadOnlyField(source='question.level')
 
     class Meta:
-        model = PaperQuestion
+        model = AnswerDetail
         fields = ['id', 'question', 'name', 'options', 'type', 'level',
                   'total_score', 'questioncat_name', 'img', 'user_answer', 'score', 'is_right']
diff --git a/server/apps/exam/views.py b/server/apps/exam/views.py
index b80ef21..3b4f96a 100644
--- a/server/apps/exam/views.py
+++ b/server/apps/exam/views.py
@@ -287,6 +287,7 @@ class ExamViewSet(CreateUpdateCustomMixin, ModelViewSet):
         return Response(status=204)
 
     @action(methods=['post'], detail=True, perms_map=[{'post': '*'}], serializer_class=Serializer, permission_classes = [IsAuthenticated])
+    @transaction.atomic
     def start(self, request, *args, **kwargs):
         """
         开始考试
@@ -371,6 +372,7 @@ class ExamRecordViewSet(ListModelMixin, DestroyModelMixin, GenericViewSet):
         return self.get_paginated_response(serializer.data)
     
     @action(methods=['post'], detail=True, perms_map=[{'post': '*'}], serializer_class=ExamRecordSubmitSerializer, permission_classes = [IsAuthenticated])
+    @transaction.atomic
     def submit(self, request, pk=None):
         '''
         提交答卷
@@ -415,4 +417,4 @@ class ExamRecordViewSet(ListModelMixin, DestroyModelMixin, GenericViewSet):
         er.end_time = now
         er.is_submited = True
         er.save()
-        return Response()
\ No newline at end of file
+        return Response(ExamRecordListSerializer(instance=er).data)
\ No newline at end of file