when.whileas的区别用法借鉴.pdf
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when, while 和 as 的用法
一．when，while ，as 在时间状语从句中的区别：
①三者均可表示 “当…… 的时候 ”，如果主句表示的是短暂的动作， 而从句表
示的是一段时间，三者可通用。如：
I met Kang Li as ／when ／while I was walking along the street ．当我沿街散步时碰
见了康丽。
②when 可以和延续性动词连用，也可以和短暂性动词连用；而 while 和 as
只能和延续性动词连用。 如：
It was snowing when we got to the airport．当我们到达机场时，天正下着雪。（不
能用 while ）
③ as 强调主句与从句表示的动作同时发生， as 常表示 “随着 ……”； 一“
边 …… ，一边 …… ；while 强调主句表示的动作持续于 while 所指的整个时间内；
when 可指主、从句所述动作同时或先后发生。如：
As the time went on ，the weather got worse ．（as 表示 随着“ ……”之意）
He sang as he went along．他边走边唱。
Please write while I read．我读的时候，请写下来。
When he reached home，he had a little rest．回到家后，他休息了一会儿。
④when 用于表示 一“……就 ……”的句型中（指过去的事情）。
somebody had hardly （＝scarcely ） done …when ．．．＝ Hardly ／ Scarcely had somebody
done …when ．．．
①I had hardly ／scarcely closed my eyes when someone knocked at the
door ．＝Hardly ／ Scarcely had I closed my eyes when someone knocked at
the door ．我刚一闭上眼，就有人在敲门了。
二.when, while 和 as都可引导让步状语从句：
①． when 引导让步状语从句，意为“尽管，虽然”相当于 though 或 although:
They stopped trying when they might have succeeded next time.
②while 引导让步状语从句，相当于 although ，是较为正式的书面语 :
While I am willing to go, I would like it better that you went.
③as 引导让步状语从句必须倒装，从句中的表语，状语或动词原形置于句首，
若表语为名词，前置时省略冠词。
Child as he is, he knows a lot.
Much as I like it, I will not buy it, for it ’s too expensive.
Try as he might, he couldn ’t find a job.
三 .when 和 while 可用作并列连词 :
①when作并列连词，意为“突然，正在那个时候”常运用于以下句型中：
Somebody be about to do , when,
Somebody be on the point of
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