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.
