作业精灵老师示例：
1：S1：How does Su Hai go to school？
S2：She goes to school by bus.
2：S1：How does Mike go to school？
S2：He goes to school by metro.
3：S1：How does Yang Ling go to school？
S2：She goes to school on foot.
4：S1：How does Liu Tao go to school？
S2：He goes to school by taxi.
