bug fixes

src/pages/learn/courseDetail.vue

@@ -273,7 +273,7 @@
                   {{ $t('pages.learn.courseDetail.Status') }}{{ tabs[3].assess.essay.status }}
                 </div>
                 <div class="status-text" v-if="tabs[3].assess.essay.created_time">
-                  {{ $t('pages.learn.courseDetail.Submissiontime') }}{{ tabs[3].assess.essay.created_time }}
+                  {{ $t('pages.learn.courseDetail.Submissiontime') }}：{{ tabs[3].assess.essay.created_time }}
                 </div>
                 <div class="status-text">
                   {{ $t('pages.learn.courseDetail.score2') }}{{ tabs[3].assess.essay.score }}