input 失去焦点，是由key变化引起的

src/features/OnlineExam/Examing/FillBlankQuestionView.vue

@@ -9,7 +9,7 @@
     </div>
     <div
       v-for="(option, index) in studentAnswer.split('##')"
-      :key="examQuestion.id + index"
+      :key="examQuestion.questionId + index"
       class="option"
     >
       <span class="question-options">{{ index + 1 }}. </span>