英语里面while和when的用法和区别

when,while 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只能和延续性动词连用。 ① Why do you want a new job when you've 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。 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都可使用。 ①When ／While 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 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．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。