   selectedAnswers: [],
          result: null,
          quizOver: false,
          mode: 'sequential', // sequential or random
          currentQuestion: null,
          loading: true // 添加加载状态
        };
      },
      computed: {
        modeLabel() {
          return this.mode === 'sequential' ? '切换为随机模式' : '切换为顺序模式';
        }
      },
      methods: {
        async fetchQuestions() {
          this.loading = true; // 开始加载时设置加载状态为 true
  