as,when,while的区别当……的时候的区别

as,when,while的区别当……的时候的区别
as,when,while的区别
当……的时候的区别

as,when,while的区别当……的时候的区别
when,while,as引导时间状语从句的区别
when,while,as显然都可以引导时间状语从句,但用法区别非常大.
一、when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.
① Why do you want a new job when youve got such a good one already?（get为短暂性动词）你已经找到如此好的工作,为何还想再找新的?
②Sorry,I was out when you called me．（call为短暂性动词）对不起,你打电话时我刚好外出了.
③Strike while the iron is hot．（is为延续性动词,表示一种持续的状态）趁热打铁.
④ The students took notes as they listened．（listen为延续性动词）学生们边听课边做笔记.
二、when从句的谓语动词可以在主句谓语动作之前、之后或同时发生；while和as从句的谓语动作必须是和主句谓语动作同时发生.
1．从句动作在主句动作前发生,只用 when.
①When he had finished his homework,he took a short rest．（finished先发生）当他完成作业后,他休息了一会儿.
②When I got to the airport,the guests had left．（got to后发生）当我赶到飞机场时,客人们已经离开了.
2．从句动作和主句动作同时发生,且从句动作为延续性动词时,when,while,as都可使用.
①When ／While ／As we were dancing,a stranger came in．（dance为延续性动词）当我们跳舞时,一位陌生人走了进来.
②When ／While ／As she was making a phonecall,I was writing a letter．（make为延续性动词）当她在打电话时,我正在写信.
3．当主句、从句动作同时进行,从句动作的时间概念淡化,而主要表示主句动作发生的背景或条件时,只能用 as.这时,as常表示“随着……”；“一边……,一边……”之意.
① As the time went on,the weather got worse．（as表示“随着……”之意）
② The atmosphere gets thinner and thinner as the height increases．随着高度的增加,大气越来越稀薄.
③As years go by,China is getting stronger and richer．随着时间一年一年过去,中国变得越来越富强了.
④The little girls sang as they went．小姑娘们一边走,一边唱.
⑤The sad mother sat on the roadside,shouting as she was crying．伤心的妈妈坐在路边,边哭边叫.
4．在将来时从句中,常用when,且从句须用一般时代替将来时.
①You shall borrow the book when I have finished reading it．在我读完这本书后,你可以借阅.
②When the manager comes here for a visit next week,Ill talk with him about this．下周,经理来这参观时,我会和他谈谈此事.
三、when用于表示“一……就……”的句型中（指过去的事情）.
sb．had hardly（＝scarcely） done sth．when．．．＝Hardly ／ Scarcely had sb．done sth．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.
②I had hardly ／scarcely entered my room when the telephone rang．＝Hardly ／Scarcely had I entered my room when the telephone rang．我刚一走进房门,电话就响了

1.when所引导的时间状语从句,其中的谓语动词既可以延续的,又可以是非延续的.并且与主句中的谓语动词的发生没有先后顺序(无所谓发生在主句动词之前,同时或之后).
而while引导的时间状语从句，其中的谓语动词只能是延续性的,并且与主句中的谓语动词要同时发生.
例:
When he came,I was mending my bike.
不能说While he c...

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1.when所引导的时间状语从句,其中的谓语动词既可以延续的,又可以是非延续的.并且与主句中的谓语动词的发生没有先后顺序(无所谓发生在主句动词之前,同时或之后).
而while引导的时间状语从句，其中的谓语动词只能是延续性的,并且与主句中的谓语动词要同时发生.
例:
When he came,I was mending my bike.
不能说While he came,I was mending my bike.
(came是非延续性动词)
2.while引导的时间状语从句多用于进行时态(主句和从句都同时进行,一边...,一边...)，而when一般用法较普遍.
While he was doing his homework,his mother was cooking.
He was a great scientist when he was young.
3.as作“当……的时候”时引导短暂性动作的动词。
As he went into the room,the man stopped shouting.
（这句也可以用when)
当从句表示"随时间推移"连词只能用as，不能用when或while.
As the days went by,he became stronger.

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