过去被打断的动作，过去连续中断动作
用过去进行时来表示过去一个较长的动作被打断了。打断通常是简单过去时较短的动作。其实，这可能是一个真正的干扰，也可能只是一个时间上的干扰。
例如：
I was watching TV when she called.
她打电话时我正在看电视。
She was writing a letter when the telephone rang.
电话铃响时，她正在写信。
While we were having a picnic, it began to rain.
当我们正在野餐时，天开始下雨了。
What were you doing when the earthquake started?
地震开始的时候你在做什么?
I was listening to my iPod, so I didn't hear the fire alarm.
我当时在听iPod，所以没有听到火警。
You didn't listen to me when I told you to turn off the oven.
我让你把烤箱关掉的时候你根本没听我的。
Someone stole John's car while he was sleeping last night.
昨晚约翰睡觉时，有人偷了他的车。
Sammy was waiting for us when we got off the plane.
我们下飞机时萨米在等我们。
When I was writing an E-mail, the computer suddenly shut down.
当我正在写电子邮件时，电脑突然关机了。
What were you doing when you broke your leg? I'm skiing.
你摔断腿的时候在干什么?我在滑雪。
所以，当过去被打断的动作，一般用过去进行时。