一、过去进行时除了可以表示过去某段时间发生的事情外，也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。例如：
1. What was she doing at nine o'clock yesterday？
昨天晚上九点她在做什么？（介词短语表示时间点）
2.Tom was getting up at six o’clock every day that week.
汤姆那一周里每天都是六点钟起床。
3.I was washing my clothes at this time yesterday．
昨天的这个时候，我正在洗衣服。
4.They were playing games at 5：00 p.m. yesterday．
昨天下午五点他们正在玩游戏。
5. What were you doing in the classroom yesterday afternoon?
昨天下午你在教室里干什么?
6. When I saw him he was decorating his room.
当我看见他的时候他正在装饰房间。（when从句表示时间点）

二、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。例如：
1. While he was waiting for the bus，he was reading a newspaper.
他边等车边看报。（两个动作都是延续的）
2.He was cleaning his car while I was cooking.
他擦车时我在做饭。（两个动作同时进行）
3.They were singing while we were dancing.
我们跳舞的时候他们正在唱歌。
4.When I was doing my homework,my mother was cooking.
当我正在做功课的时候，我妈妈正在做饭。
5.When my mother was doing the housework,my father was watching TV.
当我妈妈正在做家务的时候，我爸爸正在看电视。