过去进行时

1.概念：表示过去某段时间或某一时刻正在发生或进行的行为或动作。

2.时间状语：at this time yesterday, at that time或以when引导的谓语动词是一般过去时的时间状语等。

3.基本结构 主语 was/were doing 其他

4.否定形式：主语 was/were not doing 其他

5.一般疑问句：把was或were放于句首。(第一个字母大写）

6.例句：At that time she was working in a PLA unit.

           When he came in, I was reading a newspaper.