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.小姑娘们一边走,一边唱。 ⑤The sad mother sat on the roadside,shouting as she was crying.伤心的妈妈坐在 路边,边哭边叫。 4.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。