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状语从句是一较大的语法项目，也是近几年高考题中常见的一个重要试点。 下面是着重为大家讲解：时间状语从句中when, while, as的区别 1)when引导从句时，主从句的动作有先有后，也可以同时进行,从句的动作可以是持续性的，也可以是短暂的。 如：
When I got to the airport, the plane had already taken off. （主先从后）（短暂性）
When I lived there, I used to go to the seaside on Sundays. (同时) （持续性）
When the movie ended, the people went back. （从先主后） 2)while侧重主从句动作的对比，且从句的动词必须是持续性的。 如：
While we were chatting she was looking at the time table on the wall． 3)as引导从句时侧重主从句动作同时或几乎同时进行，从句的动作可以是持续性的，也可以是短暂的。
如：
Sometimes I watch TV as I am having breakfast． 4）when和while还可以是并列连词，意思分别是“就在这时”，“然而”。
如：
I was having a rest on the sofa when the telephone rang．
They were surprised that a child should work out the problem while they couldn’t . 注：并列连词when常用与以下句型中：
①…was/were doing…when…（正在做…突然）
②…was/were about to do…when…（刚要做…突然）
③…was/were on the point of doing…when…(刚要做…突然)
④…had just done…when….(刚一…就)
⑤Hardly/Scarcely had…done…when…(刚一…就) 好了，以上就是关于时间状语中when, while, as区别的介绍，还请大家在平时勤加练习。 | 
