City University of Hong Kong CLASS CLASS
Making Sense of Grammar
+1 vote
为什么有时候"当...的时候"必须得用while?
asked Mar 14 in Questions about English Grammar by 116030300105lwt (240 points)

1 Answer

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一、when既可表示某一点时间,也可以表示某一段时间 。在when引导的时间状语从句中,其谓语动词可以是延续性的,也可以是非延续性的,可与主句中的谓语动词同时发生,也可在其后发生。
例如:
(1)I was just reading a book when she came into my room.她走进我房间时,我正在看书.
(2)Were you writing when the teacher came in?老师进来的时候,你在写信吗?
(3)When he was a child he was always trying out new ideas.他小时候就常常试验一些新的设想.
二、while只能表示某一段时间,不能表示某一点时间。在while引导的时间状语从句中,其谓语动词只能是延续性的,而且也只能与主句中的谓语动词同时发生或存在。
例如:
(1)While Jim was mending his bike,Lin Tao came to see him. 正当吉姆修自行车时,林涛来看他.
(2)You can't do your homework while you're watching TV.你不能一边看电视一边做家庭作业.
三、when和while的区别还在于:while引导的时间状语从句多用进行时态,而when引导的时间状语从句多用一般时态。

answered Mar 19 by 116060100127wjl (280 points)
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