四、根据括号内的汉语提示完成对话。
A: Hello, Mary! It's half past six now. Where are you going?
B: I'm going to school.
A: How do you get to school?
B:16. ____________ (乘校车).
A: So early?
B: Yes. If so, I can have enough time to Chinese.
A:17. ____________ (通过阅读学习汉语吗)?
B: Yes. It's one of my ways of learning it. I made a Chinese friend, Li Li.
A: How do you keep in touch with her?
B:18. ____________ (通过电子邮件).
A: Oh, you can practice your Chinese writ this way.
B: Yes, you're right. Sometimes I pract speaking Chinese 19. ____________ (通过给她打电话).