初二英语：when和while什么区别

一。引导时间状语从句时，WHILE连接的是时间段，而WHEN连接的多是时间点
例如What does your father do while your mother is cooking?
What does your mother do when you come back?
二，WHILE可以连接两个并列的句子，而WHEN不可以
例如I was trying my best to finish my work while my sister was whtching TV
三，WHEN是特殊疑问词，对时间进行提问，WHILE不是。
例如，When were you bron?

1）as, when 引导短暂性动作的动词。
Just as / Just when / When I stopped my car, a man came up to me.
2）当从句的动作发生于主句动作之前，只能用when 引导这个从句，不可用as 或 while。
When you have finished your work, you may have a rest.
3）从句表示"随时间推移"连词能用as，不用when 或while。
As the day went on, the weather got worse.
日子一天天过去，天气越变越坏。

主句应为过去式的

when后接短暂性动词和持续性动词均可
while后接持续性动词
以上是他们最根本的区别，这样就能很清楚了吧？

when通常和be about to 连用
如：I was about to go out when it began to rain.
当天开始下雨时，我正准备出门。
while通常跟进行时
as有随着——的意思
As it was getting dark,I felt very scared.
随着天渐渐黑下来，我十分害怕。
while可以表示语气转折，如：Wh