as when while since 引导时间状语时怎么用

as when while since 引导时间状语时怎么用

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和as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? ② Sorry,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. ③ Strike 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. ④ As 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. ⑤ The little girls sang as they went．小姑娘们一边走,一边唱. ⑥ The 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,I’ll 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. 四．其它情况 1> When 还可以作并列连词 “这时”的意思. 常用于 be about to do when, be doing when , be on the point of doing when, 以及 had hardly/scarcely done… when…结构中. Eg: I was about to go out when the teacher came in . 我正想出去,这时候老师进来了. He had hardly sat down when his mobile rang. 2> While 引起让步状语从句,意思是“虽然…但是….”、“尽管…但是…”(多放于句首) While he loves his students,he is very strict with them.. 虽然他爱他的学生,可是他对他们很严格. 3> While 还能作并列连词 “而,然而” 表示对比. Some people waste food while others haven't enough. 有些人很费粮食,然而有些人却吃不饱. The son was having a good meal at home,while the parents were working in the fields. 儿子在家吃好饭而父母却在田里辛勤劳作. 五．练习： 1 He will write to you as soon as he ____ to Shanghai. A. gets B. is getting C. will get D. shall get 2 He was about to tell me the secret _____ someone patted him on the shoulder. A. as B. while C. when D. until 3 ____ mother got home, I was tidying my room. A. While B. When C. As soon as D. Before 4 The teacher didn’t begin her class ______ the students stopped talking. A .until B. because C. after D. when . 5 ---Why didn’t you help the little boy? ---He had struggled to his feet_____ I reached him. A. after B. till C. before D. when 6 You must make your new house clean and safe_____ you move in . A. because B. when C. before D. until 7 I was so familiar with her that I recognized her voice _____ I pick up the phone. A. after B. the moment C. while D. before. 8 Mr. Wang likes popular songs______ his wife likes classical music. A. when B. while C. if D. so 9 ___ life pace continues to speed up, we are quickly losing the art of enjoyment. A. With B. When C. As D. While 10 The door of the lift was closed _____ I could enter in. (还没来得及…就…) A. as B. since C. until D. before. 11 ____ he grew older he became interested in gardening. A. As B. That C. During D. If 12 ---How long has your family lived here ? --- _________1932. A. After B. In C. From D. Since 13 I enjoy visiting friends ______ my sister would rather stay at home. A .when B. while C. after D. as. 14 By the end of last year, we _______ 700 English words. A .have learned B. learned C. would learn D. had learned. 15 ___ you have made a promise , you should carry it out . A. Until B. Once C. For D. As soon as while和as引导的时间状语从句,什么时候只能用其中一个,不能用两一个代替? as, while和when均可用作从属连词,引导时间状语从句,作“当……时候”解.它们所引导的时间状语从句有时意思一样,有时却有差异.意思相同时,这三个词可以互换使用；意思不同时,则不能互换. 一、 as的意思是“正当……时候（just as,at the same moment that）”“随着……(while,when)”,它既可表示一个具体的时间点,也可以表示一段时间.as可表示主句和从句的动作同时发生或同时持续,即“点点重合”“线线重合”；又可表示一个动作发生在另一个动作的持续过程中,即“点线重合”,但不能表示两个动作一前一后发生.如果主句和从句的谓语动词都表示持续性的动作,二者均可用进行时,也可以一个用进行时,一个用一般时或者都用一般时.例如： 1. As I got on the bus, he got off. 我上车,他下车.（点点重合） 2. He was writing as I was reading. 我看书时,他在写字.（线线重合） 3. The students were talking as the teacher came in. 老师进来时,学生们正在讲话.（点线重合） 二、while的意思是“在……同时（at the same time that )”“在……期间(for as long as, during the time that）”.从while的本身词义来看,它只能表示一段时间,不能表示具体的时间点.在时间上可以是“线线重合”或“点线重合”,但不能表示“点点重合”.例如： 1. He was watching TV while she was cooking. 她做饭时,他在看电视.（线线重合） 2. He was waiting for me while I was working. 我工作的时候,他正等着我.（线线重合） 3. He asked me a question while I was speaking. 我在讲话时,他问了我一个问题.（点线重合） 三、 when的意思是“当……时候（at the time that）”“无论什么时候（whenever）” “一……就……（as soon as ）” “在……以后（after）”.它表示的时间概念比较广泛,上述例句中的as或while均可用when代替,因为when不但可以表示具体的时间点,而且也可以表示一段时间.在时间上它既能表示“点点重合”“线线重合”,又能表示“点线重合”.例如： 1.When he came in, she went out. 他进来,她出去.（点点重合） 此句中when从句的动作表示的是一个时间点,when可以用as代替,但不能用while代替. 2. When he came back, I was doing some washing. 他回来时,我在洗衣服.（点线重合） 此句中when从句的动作表示的是一个时间点,所以只能用as代替,不能用while代替. 3. When Mary was writing a letter, the children were playing outside. 玛丽写信时,孩子们都在外面玩.（线线重合） 此句中的when从句的动作表示的是一段时间,故可用as 或 while代替. since KK: [] DJ: [] ad.(常用于现在完成时或过去完成时) 1. 此后;从那时到现在 She left school three years ago and has worked as a nurse ever since. 她三年前毕业,从那时起便一直当护士. 2. 之前,以前 prep. 1. (常用于现在完成时或过去完成时)自...以来,从...至今 I haven't heard from him since last year. 我自去年以来未曾收到过他的信. conj. 1. (常用于现在完成时或过去完成时)自...以来,从...至今 It's been ten years since they married. 他们结婚到现在已经十年了. She has been living a hard life since her husband died. 她自从丈夫死后,一直过着艰苦的生活. 2. 既然;因为,由于 He must have taken the book since it isn't here. 他一定是把书拿走了,因为书已不在这里了. Since it is so hot, let's go swimming. 既然天气这么热,我们去游泳吧