时态之间的逻辑联系

过去时与过去进行时

主语+过去进行时+when+过去时

某某当时正在干什么，突然......

I was watching TV when the telephone rang.

我当时正在看电视的时候，突然电话铃响了。

We were having dinner when it rained.

我们当时正在吃晚饭的时候，突然下雨了。

I was doing homework in my bedroom when my mum came in with the dog.

我当时正在我卧室里做作业的时候，突然妈妈带着狗进来了。

一位农民当时正在田里干活的时候，突然，一辆火车从桥上掉了下来。

A farmer was working in the field when a train fell off the bridge.

我们当时正在教室里上英语课的时候，突然空调不工作了。

We were having English classes in the classroom when the air-conditioner didn’t work.