进行时态或一般将来时态
1、was/were doing +when 意思为“就在这时，正在这时”。
如：
I was walking in the street when someone called me from behind. 我正在街上走，就在这时有人从后面叫我。
They were discussing the problem when the teacher came in. 他们正在讨论问题，就在这时老师进来了。
2.was/were about to do...when 意思为 “正要/正准备做某事，就在这时……”。
如：
She was about to go out when an unexpected visitor came. 她正准备出去，这时来了一位不速之客。
We were about to set out when it began to rain. 我们正要动身，就在这时开始下雨了。
3.be+表示状态的介词短语+when意思为 “正在做某事，就在这时……”。
如：
They were at work in the office that afternoon when a big fire broke out.那天下午他们正在办公室工作，就在这时一场大火发生了。
We were on duty in the classroom when a boy rushed in. 我们正在教室里值日，就在这时一名男孩冲了进来。
Li Ping was on his way home when two boys stopped him.李平正往家走，突然两个男孩拦住了他。
什么时态中when表示就在此时
1、将when翻译成当……时候，此时主句与从句时台一样.2.将when翻译成……就在这时.有三个常用句型3.Be doing sth.when……正在做什么，就在这时
