when while as 区别

when while as 区别
when while as 区别

when while as 区别
when,as,while这三个词都可以引出时间状语从句,它们的差别是：when 从句表示某时刻或一段时间,有“当……时”的意思；
as 从句表示进展过程,有“随着,一边……一边”的意思；
while 只表示一段持续的时间,有“在……的同时”的意思.
例如：
When he arrived home,it was just nine o'clock.
当他到家时,正是九点钟.
As he grew older,he became more intelligent.
随着他年龄的增长,他变得更有才智了.
While she was typing the letter,the telephone rang.
当她在用打字机打那封信时,电话响了.

When 可以用一般现在是，过去时还有进行时
While 只能用进行时
As 随着。。
当然这些都是在时间状语从句中的

when, while ,as soon as
这三个词都有"当……时候"之意，但用法有所不同，使用时要特别注意。
①when意为"在……时刻或时期"，它可兼指"时间点"与"时间段"，所引导的从句的动词既可以是终止性动词，也可是持续性动词。如：
When I got home, he was having supper.我到家时，他正在吃饭。
When I ...

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when, while ,as soon as
这三个词都有"当……时候"之意，但用法有所不同，使用时要特别注意。
①when意为"在……时刻或时期"，它可兼指"时间点"与"时间段"，所引导的从句的动词既可以是终止性动词，也可是持续性动词。如：
When I got home, he was having supper.我到家时，他正在吃饭。
When I was young, I liked dancing.我年轻时喜欢跳舞。
②while只指"时间段"，不指"时间点"，从句的动词只限于持续性动词。如：
While I slept, a thief broke in.在我睡觉时,盗贼闯了进来。
辨析
①when从句与主句动作先后发生时，不能与while互换。如：
When he has finished his work, he takes a short rest.每当他做完工作后，总要稍稍休息一下。(when = after)
When I got to the cinema, the film had already begun.当我到电影院时，电影已经开始了。(when=before)
②when从句动词为终止性动词时，不能由while替换。如：
When he came yesterday, we were playing basketball.昨天他来时，我们正在打篮球。
③当从句的谓语是表动作的延续性动词时，when, while才有可能互相替代。如：
While / When we were still laughing, the teacher came in.正当我们仍在大声嬉笑时，老师进来了。
④当从句的谓语动词是终止性动词，而且主句的谓语动词也是终止性动词时,when可和as通用，而且用as比用when在时间上更为紧凑，有"正当这时"的含义。如：
He came just as (or when) I reached the door.我刚到门那儿，他就来了。
⑤从句的谓语动词如表示状态时，通常用while。如：
We must strike while the iron is hot.我们应该趁热打铁。
⑥while和when都可以用作并列连词。
Mike is tall while his brother is short.迈克的个子很高，然而他弟弟很矮。
Mary was on her way home when two big boys stopped her.玛丽正走在回家的路上，这时两个大个子男孩拦住她。
as soon as的用法：
（1）、as soon as one can
= as soon as possible 表示“尽可能快”之意，如：
① You must ring me up as soon as you can.
你必须尽快给我打电话。
② Please write to me as soon as possible.
请尽早给我写信。
（2）、as soon as 引导时间状语从句，表示“一……就……”。如果主句用将来时或情态动词或祈使句，从句必须用一般现在时代替将来时。如：
I’ll tell him the news as soon as he comes.
他一来我就告诉他那消息。
She may come as soon as she finishes the work.
事情一做完她就可以来。

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