when和while 他们的区别 比如 I was waiting for you when you came in.和While I was waiting for you,yoI was waiting for you when you came in.While I was waiting for you,you came in.

when和while 他们的区别 比如 I was waiting for you when you came in.和While I was waiting for you,yoI was waiting for you when you came in.While I was waiting for you,you came in.
when和while 他们的区别 比如 I was waiting for you when you came in.和While I was waiting for you,yo
I was waiting for you when you came in.While I was waiting for you,you came in.

when和while 他们的区别 比如 I was waiting for you when you came in.和While I was waiting for you,yoI was waiting for you when you came in.While I was waiting for you,you came in.
（一）、when,while都有“当……时候”的意思.
　　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）、另外,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.
　　例如：
　　1、While they were talking ,the bell rang.
　　正在他们谈话的时候,上课铃响了.
　　2、I was doing my homework when my mother came back home yesterday evening.
　　昨天晚上妈妈回家的时候,我正在做家庭作
　　注意：
　　1) 如主句谓语动词表示的是短暂动作,从句时间状语指一段时间,when while as 三者可通用.
　　例如：
　　Peter came in while /as I was watching TV.当Peter进来的时候我正在看电视.
　　I was watching TV when Peter came in.当Peter进来时我正在看电视.
　　2) as 和 when 可与非延续性动词连用,而 while 只能与延续性动词连用.
　　例如：He came in when/ as I was going to bed.我正要上床睡觉,他进来了.
　　3) as 和 while可用来指一段时间,但 as 强调主句与从句表示的动作同时发生,while强调主句表示的动作是在 while 从句的动作延续中发生.
　　例如：
　　As my mother sang those old songs,tears ran down her cheeks.
　　当我妈妈唱起那些老歌时,眼泪顺着她的脸颊流了下来.
　　I came in while he was reading an interesting book in his room.

when表示时间上的先后。
while表示两者在同时做什么事情。

when是和重句同时发生
while是主语动作发生在重句动作的过程中

初二还是初三的知识
when 和while的用法区别
①when是at or during the time that, 既指时间点，也可指一段时间；
while是during the time that，只指一段时间，因此when引导的时间状语从句中的动词可以是终止性动词，也可以是延续性动词，而while从句中的动词必须是延续性动词。
②when 说明从句...

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初二还是初三的知识
when 和while的用法区别
①when是at or during the time that, 既指时间点，也可指一段时间；
while是during the time that，只指一段时间，因此when引导的时间状语从句中的动词可以是终止性动词，也可以是延续性动词，而while从句中的动词必须是延续性动词。
②when 说明从句的动作和主句的动作可以是同时，也可以是先后发生；while 则强调主句的动作在从句动作的发生的过程中或主从句两个动作同时发生。
③由when引导的时间状语从句，主句用过去进行时，从句应用一般过去时；如果从句和主句的动作同时发生，两句都用过去进行时的时候，多用while引导，如：
a. When the teacher came in, we were talking.
当此句改变主从句的位置时，则为：
While we were talking, the teacher came in.
b. They were singing while we were dancing.
④when和while 还可作并列连词。when表示“在那时”；while表示“而，却”，表对照关系。如：
a. The children were running to move the bag of rice when they heard the sound of a motor bike.
孩子们正要跑过去搬开那袋米，这时他们听到了摩托车的声音。
b. He is strong while his brother is weak.
他长得很结实，而他弟弟却很瘦弱。
具体你可以参考这一段。
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
重点是—.①

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