（优质）when和while用法比较

when和while用法比较When所引导的从句谓语动词可以是延续性动词，也可以是非延续性动词；从句的时态多用一般现在时或一般过去时。例句：The train had left when I got to the station.例句：I met one of my old friends when I was walking in the street yesterday.而while引导的主从复合句则通常都为延续性的动词，因而常常使用进行时态。例句：My mother was cooking while my father was watching TV.例句：One boy is rowing while the other boy in the boat is dangling around his legs in the cool water of the lake.一个男孩正在划船，而船里的另一个男孩则把腿悬垂在凉爽的湖水中。2、when 可以用于 be about to do sth. when .的固定结构当中例句：I was just about to call you when you called me.例句：When I arrived home, my mother was cooking.当我到家进，妈妈正在做饭。例句： I get the giggles when I'm nervous.我紧张时就不停地咯咯大笑。While所引导的从句谓语必须是延续性动词；从句一般要用进行时态，如果主句和从句的动作时同时进行的，则主句也应为进行时态。例句3： The telephone rang while I was watching TV.当我在天电视时，电话铃响了。例句4： I was writing a letter while my father was reading a newspaper.我爸爸在看报纸时，我正在写信。例句5： I will finish my homework while you help me clean the room.你帮我打扫房间的时候我会做完我的作业。另外，作连词时，while还有一个意思是“然而，尽管”，这个意思是when所没有的，在考试中也会经常出现。例句6： While I am willing to help, I do not have much time available.尽管我愿意帮忙，但是没有多少时间。He is short while his brother is tall.Tom has opened his own business while his classmates are still slogging away at school.当汤姆的同学还在学校苦读时，他已经开始了自己的事业。while还可以引导让步状语从句“尽管”While everyone else wouldn't go to the mountain area, he went without a second thought.