when, if, before, until从句.doc

when if before until引导的从句 由一个主句和一个或多个从句构成的句子叫复合句。主句是复合句的主干部分，从句是修饰主句或主句的某个成分的。从句不能单独成句，但具有主语和谓语，须由关联词引导。根据从句在主句中充当不同的成分，可分为不同的从句，例如，主语从句、宾语从句、表语从句、同位语从句、定语从句、状语从句等。由when, if, before, until引导的从句一、when引导的时间状语从句(1) when引导时间状语从句时，表示“当的时候” when既可以指时间段也可指时间点Her brother was very fat when he was a child. 她哥哥小时候很胖。They were talking when the teacher came in.老师进来的时候，他们正在讲话。 when从句中既可用延续性动词又可用非延续性动词You should keep your room clean and tidy when you live here.在你住在这里的时候，你应该保持你房间干净、整洁。When he arrives, hell tell us about the match.他回来的时候就会告诉我们比赛的情况。 when从句动作既可和主句的动作同时发生又可在主句的动作之前或之后发生 Mary was doing her homework when her father was reading newspapers.玛丽的爸爸在看报纸的时候她正在做作业。Ill call you when I get to the airport. 我一到机场就给你打电话。二、if引导的条件状语从句条件状语从句表示主句动作发生的条件，条件有真实和非真实两种。if引导条件状语从句时，意为“如果，假如”，表示在某种条件下，某事很可能发生。if除了引导条件状语从句，还可引导宾语从句。if引导的条件状语从句和宾语从句的区别：（1）if 在句中的含义不同If 在宾语从句中翻译为“是否”,相当于whetherI want to know if he is a teacher.If 在条件状语从句中翻译为“如果”Ill go to see you if I am free next week.（2）if 在从句中的位置不同：If 引导的宾语从句放在主句之后，做宾语；而if引导的状语从句可放在主句之前也可放在主句之后，If 引导的条件状语从句放于句首时多用逗号隔开I dont know if the train has arrived.I will go out tomorrow if it doesnt rain.= If it doesnt rain, I will go out tomorrow.（3） 时态要求上有区别1.I want to know if there will be a sports meeting next month.If 引导的宾语从句的时态由主句及本身时态决定；2.If it rains , well hold it.If 引导条件状语从句的时态为一般现在时， 记住“主将从现” 三、before和until引导的状语从句（1）before表示“在 之前”，而until表示“直到才”，一般情况下，两者可以互用。主句肯定表示主句动作的终止时间，主句否定强调动作的起始时间。1. 主句为否定时，谓语动词为非延续性动词。常见的动词有open, start, leave, go, arrive, finish, begin, stop, etc. 1) The noise of the street didnt stop before/until it was midnight.2) The children wont come back until/before it is dark.3) I didnt leave the lonely boy before/until his mother came home.2. 主句为肯定式，谓语为延续性动词。这类动词有：stand, live, stay, talk, be, wait, etc.1). He lived with his parents until/before he graduated from school.2). I will wait before/until he comes to my help.3). I shall stay here until/before you come back.（2）下列情况下宜用before不用until.1、主句为肯定式，谓语为非延续性动词时只用before.1) He fell asleep before I could take off his clothes.2) We arrived there before it started to rain.3) The holiday came to an end before I knew it.2、 主句谓语动词强调动作的迟缓性，只用before，这时常伴有时间段状语或时间段暗示。It was quite a long time before he found the elephant.过了很长时间，他才找到大象。We had walked a long way before we found some water.走了很长的路我们才找到水。It was midnight before my brother came home.我哥哥直到半夜才回来。3、 如果强调从句谓语动作未发生就发生主句谓语动作，只用before,这时常译为“未及（不等）就” 1)We can leave early in the morning before it gets too hot.趁天还不太热，我们上午早点离开。2)I must write it down before I forget it.趁我还未忘，我必须把它记下来。4、 表示“与其说倒不如”,“与其毋宁”的意思时只用before.I would give up my job before I agree to be dismissed. 我与其被解雇还不如先辞职。He will die of hunger before he steals.他宁愿饿死也不愿意去偷。5在某些特定句型中用before。It was (not) long before（不久）过了很长时间才It will (not) be long before（不到）要过很长时间才会It will probably not be long before they understand each other. 他们大概过不久就会互相了解。It was not long before the whole country rose up.不久全国人民就奋起反抗。（3）下列情况一般使用until1、主句是延续性谓语动词时，肯定,否定都可以，但意义完全不同，肯定表示动作终止，而否定表示动作开始。For example:1).We discussed the problem until/before he came back. 我们一直讨论到他回来。2).We didnt discuss the problem until he came back. 我们一直等他回来才讨论问题。2、Notuntil句型，尽管在某些情况下可与before互换使用，但在强调句中一般仍用until; 1). It was not until he told me that I knew it.直到他告诉我我才知道这件事。2).It was not until he finished his homework that he went home.直到完成作业他才回家。3放于句首时用until. Until he finished his homework ，he didnt go home. 直到完成作业他才回家。应注意：在使用not until时，若not until放于句首，句子应部分倒装。Not until he finished his homework，did he go home. 直到完成作业他才回家。四、when，if，until， before引导的状语从句位置when , if和until引导的状语从句放在主句前，也可放在主句后。但是放在主句前面时，须用逗号 ，隔开。而before引导的状语从句只能放在主句后面。I want to be a teacher when I grow up.= when I grow up， I want to be a teacher 五、when， if， until, before引导的状语从句的时态用法在时间和条件状语从句里，谓语动词通常用现在时态表示将来的动作或状态。I will write to you when I come back Guangzhou.n He didnt go to bed until his father came back yesterday.n He wont go to bed until his father comes back today.n He doesnt go to bed until his father comes back every day.分析试题特点及做题思路考点：考连词，考时态做题思路： 正确理解句子意思- 判断语境提供的时态特点- 选择正确的时态一、基础题：1. When my mother returned last night, I _ a book. A. read B. am reading C. was reading D. am going to read2. What _ you _ when it began to rain?A. do, do B. were, doing C. are, doing D. did, do3. I will go to the beach _ it doesnt rain this week.A. if B. and C. until D. when4. We wont leave here _ our teacher comes back.A. until B. since C. after D. as soon as5. Youll be late _ you dont get up early tomorrow morning.A. if B. when C. before D. until6. If he _ on time, we will go without himA. doesnt come B. dont comeC. didnt come D. wont come7. If you _ him tomorrow, please ask him if he _ to work on the farm with us.A. see ; goes B. will see; goes C. will see; will go D. see; will go8. Difficulties are nothing if we _not afraid of themA. will B. shall C. are D. do9. Work hard if you _to get a good mark.A.wanted B. wanting C. want D. will want10. If you _ to the party, youll have a great time. A. will go B. went C. go D. going11. Ill wake you up when he _back.A. will B. is going to come C. comes D. come12. If you _ tired, you _ to have a rest.A. feels, have B. feel, have C. felt, had D. is feeling, have 13. If there _ fewer trees, there _ more pollution.A. are, is B. will be, will be C. are, will be D. will be, are14. She went to bed _ the TV play was over. A. until B. when C. and D. or15. I knew nothing about it _ he told me. A. and B. after C. or D. until 16. If she _ (get) up late, she _ (not catch) the early bus.A. gets, wont catch B. will get, doesnt catchC. get, wont catch D. get, catches 17. Were leaving for Shenzhen _ it is fine today. A. as B. when C. if D. whether18. I was cooking _ she knocked at the door. A. because B. until C. before D. when19. It was raining heavily_we got to Paris.A. while B. if C. when D. because20 . The volleyball match will be put off if it_. A. will rain B. rains C. rained D. is raining提高题：1. I had to finish the picture _ my mother came back.A. until B. before C. after D. while2. I dont like to be interrupted if I_.A. speak B. will speak C. am speaking D. spoke3. He was about to go to bed _ the doorbell rang.A. while B. as C. before D. when4. Where _ he _ the film if he has time?A. does, see B. do, see C. will, see D. are, see5. _ they _a match when the P.E. teacher was busy?A. Are, having B. Do, have C. Will, have D. Are, have6. I havent heard from him _ he left home. A. before B. when C. until D. because7. Take the medicine _ you go to bed. A. before B. after C. until D. because8. I wont believe it _ I hear with my own ears.A. until B. after C. because D. when9. She likes everything to be in place _ she starts to work.A. before B. after C. until D. because10. He always stay in bed _ lunch time.A. before B. after C. until D. because11. I dont like to be interrupted if I_.A. speak B. will speak C. am speaking D. spoke12. If you _the book you will understand the story better.A. will be reading B. have read C. will have read D. read13. If you _I will go with you.A. go to B. went C. will D. should go14. If he_ exercise, he_healthy.A.not; will B.isnt; wont beC.doesnt; will be D.doesnt do; wont be15. If he _, I _go swimming alone.A. doesnt come will go B. wont come; will goC. will come; wont go D. is coming; dont go难题：1. I dont know _ he is at home now.A. before B. when C. or D. if2. It will be a long time _ Peter _ his work. A. since, has finished B. after, finishesC. when, will finish D. before, finishes.3 I _ her the answer if she