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。

如：My brother fell while he was riding his bicycle and hurt himself.

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

否定形式：主语   was / were   not   doing

一般疑问句：把was或were放于句首。

4. 用法：

（1）过去进行时表示过去某段时间内持续进行的动作或者事情。

 如：We were watching TV from seven to nine last night.

（2）过去进行时可以表示在过去某个时间点发生的事情。时间点可以用介词短语、副词或从句来表示。

如：What was she doing at nine o’clock yesterday? (介词短语表示时间点)

She was doing her homework then. （副词表示时间点）

When I saw him he was decorating his room. (when从句表示时间点)

（3）在复合句中，如果主要动作和背景动作都是延续的或同时发生的，那么主从句的动词都可用过去进行时。

如：When he was waiting for the bus, he was reading a newspaper. (两个动作都是延续的)

He was cleaning his car while I was cooking. （两个动作同时进行或主句的动作发生在从句的动作过程中）