过去进行时
- 形式：was/were ding
- 用法： she was reading a book at 11:00 last night
- 否定疑问： she was not reading a book
- 补充：一件事情持续进行，另一件事情突然出现把他打断。
-- while you were sleeping，a thief sneaked in
-- while i was cooking yesterday，a friend locked at the door
短语补充
- try to do sth ：尽力做某事（第10课、13课都有用到）
- try doing sth ：决心没那么强烈
过去完成时
- 现在完成时：have/has done
- 过去完成形式：had done
- 用法：过去的之前，站在过去的时间点，回头看过去发生的事情
- before 8:00 yesterday，she had finished her homework
- 否定疑问：had not done
- 补充：过去完成/现在完成时区别
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