学生在高一阶段已经系统学习过各种时态的用法，因此本节课以复习旧知、扩充新知以及在实际中运用过去时及将来时的各种时态为主。
Teaching aims:
After learning this period, the students will be able to:
1. clarify the concepts of the past tenses and the future tenses;
2. learn more knowledge about the above two tenses;
3. use the above two tenses appropriately in certain contexts.
