when和while的区别

when和 while都可以表示“当……时候”，两者之间有相同的意思，但是又有一定的区别。

when和while的区别

（1) when 引导的时间状语从句中的谓语动词可以是非延续性动词，也可以是延续性动词、而while 从句中的谓语动词必须是延续性动词。

I was watching TV when you called me.

你打电话时我正在看电视。

hanto ran while we were walking in the park.

我们在公园里散步时，开始下雨了。

（2) when 说明从句动作和主句动作可同时发生，也可先后发生。面while 强调主句动作在从句动作发生的过程中同时发生。

When the pot fell to pieces,the girl began to realize that she was not alone,

当那个罐子摔碎时，那个女孩开始意识到她不是一个人。

（3) when 或 while 引导的时间状语从句可以相互改写，但while 引导的句子常用进行时态。

When they came in,the girl was dancing.

＝While the girl was dancing,they came in.

当那个女孩正在跳舞时，他们进来了。

（4) while 还可做并列连词，意为"而，却"， 表示"对比关系"， 有轻微的转折之意。

She is very outgoing,while her sister is a little shy.

她非常外向，而她妹妹有点儿害羞。

when的四个用法

1.When+现在分词.例如:

When sleeping,I never hear a thing.睡觉时,我什么都听不见.

2.When+过去分词.例如:

This dictionary will look nice when printed.这本词典印出来时会很好看.

3.When+名词或形容词.例如:

When a boy,he was sick all the time.小的时候,他经常生病.

4.When+介词短语.例如:

When at Rome do as the Romans do.入乡随俗.

while的具体用法 

1、“当……时候”，引导时间状语从句(从句动作必须是延续性的)。  

Please don't talk so loud while others are working.  

While I was cleaning the window，my finger was seriously cut。  

2、“虽然，尽管”相当于although，引导让步状语从句(常把while放在句首)。  

While she is a top student， she has some shortcomings. While the Internet is bridging the distance between people， it may also be breaking some home or will cause other family problems。  

3、“只要，如果”等于as long as，引导条件状语从句。  

There is hope while there is life. While you study hard， your effort will pay off。

while后面接什么

如果while后面要接动词，则必须用doing，如果do while后面接句子或短语，则不用。其中while后面直接加动词时，动词形式一般要分为两种情况。

1、如果该动词和主句主语之间为主动关系，则一般用其现在分词形式即V-ing。2、如果该动词和主句主语之间为被动关系时，则用其过去分词形式。