whenifbeforeuntil從句

1、when if before until引導的從句 由一個主句和一個或多個從句構成的句子叫復合句。主句是復合句的主干部分，從句是修飾主句或主句的某個成分的。從句不能單獨成句，但具有主語和謂語，須由關聯(lián)詞引導。根據(jù)從句在主句中充當不同的成分，可分為不同的從句，例如，主語從句、賓語從句、表語從句、同位語從句、定語從句、狀語從句等。由when, if, before, until引導的從句一、when引導的時間狀語從句(1) when引導時間狀語從句時，表示“當?shù)臅r候” when既可以指時間段也可指時間點Her brother was very fat when he was a child. 她哥

2、哥小時候很胖。They were talking when the teacher came in.老師進來的時候，他們正在講話。 when從句中既可用延續(xù)性動詞又可用非延續(xù)性動詞You should keep your room clean and tidy when you live here.在你住在這里的時候，你應該保持你房間干凈、整潔。When he arrives, hell tell us about the match.他回來的時候就會告訴我們比賽的情況。 when從句動作既可和主句的動作同時發(fā)生又可在主句的動作之前或之后發(fā)生 Mary was doing her homewo

3、rk when her father was reading newspapers.瑪麗的爸爸在看報紙的時候她正在做作業(yè)。Ill call you when I get to the airport. 我一到機場就給你打電話。二、if引導的條件狀語從句條件狀語從句表示主句動作發(fā)生的條件，條件有真實和非真實兩種。if引導條件狀語從句時，意為“如果，假如”，表示在某種條件下，某事很可能發(fā)生。if除了引導條件狀語從句，還可引導賓語從句。if引導的條件狀語從句和賓語從句的區(qū)別：（1）if 在句中的含義不同If 在賓語從句中翻譯為“是否”,相當于whetherI want to know if he i

4、s a teacher.If 在條件狀語從句中翻譯為“如果”Ill go to see you if I am free next week.（2）if 在從句中的位置不同：If 引導的賓語從句放在主句之后，做賓語；而if引導的狀語從句可放在主句之前也可放在主句之后，If 引導的條件狀語從句放于句首時多用逗號隔開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） 時態(tài)要求上有區(qū)別1.I want

5、to know if there will be a sports meeting next month.If 引導的賓語從句的時態(tài)由主句及本身時態(tài)決定；2.If it rains , well hold it.If 引導條件狀語從句的時態(tài)為一般現(xiàn)在時， 記住“主將從現(xiàn)” 三、before和until引導的狀語從句（1）before表示“在 之前”，而until表示“直到才”，一般情況下，兩者可以互用。主句肯定表示主句動作的終止時間，主句否定強調(diào)動作的起始時間。1. 主句為否定時，謂語動詞為非延續(xù)性動詞。常見的動詞有open, start, leave, go, arrive, finish,

6、 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. 主句為肯定式，謂語為延續(xù)性動詞。這類動詞有：stand, live, stay, talk, be, wait, etc.1). He lived with his parents

7、 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）下列情況下宜用before不用until.1、主句為肯定式，謂語為非延續(xù)性動詞時只用before.1) He fell asleep before I could take off his clothes.2) We arrived there before it started to rain.3) The holi

8、day came to an end before I knew it.2、 主句謂語動詞強調(diào)動作的遲緩性，只用before，這時常伴有時間段狀語或時間段暗示。It was quite a long time before he found the elephant.過了很長時間，他才找到大象。We had walked a long way before we found some water.走了很長的路我們才找到水。It was midnight before my brother came home.我哥哥直到半夜才回來。3、 如果強調(diào)從句謂語動作未發(fā)生就發(fā)生主句謂語動作，只用befo

9、re,這時常譯為“未及（不等）就” 1)We can leave early in the morning before it gets too hot.趁天還不太熱，我們上午早點離開。2)I must write it down before I forget it.趁我還未忘，我必須把它記下來。4、 表示“與其說倒不如”,“與其毋寧”的意思時只用before.I would give up my job before I agree to be dismissed. 我與其被解雇還不如先辭職。He will die of hunger before he steals.他寧愿餓死也不愿意去

10、偷。5在某些特定句型中用before。It was (not) long before（不久）過了很長時間才It will (not) be long before（不到）要過很長時間才會It will probably not be long before they understand each other. 他們大概過不久就會互相了解。It was not long before the whole country rose up.不久全國人民就奮起反抗。（3）下列情況一般使用until1、主句是延續(xù)性謂語動詞時，肯定,否定都可以，但意義完全不同，肯定表示動作終止，而否定表示動作開始。F

11、or example:1).We discussed the problem until/before he came back. 我們一直討論到他回來。2).We didnt discuss the problem until he came back. 我們一直等他回來才討論問題。2、Notuntil句型，盡管在某些情況下可與before互換使用，但在強調(diào)句中一般仍用until; 1). It was not until he told me that I knew it.直到他告訴我我才知道這件事。2).It was not until he finished his homework

12、that he went home.直到完成作業(yè)他才回家。3放于句首時用until. Until he finished his homework ，he didnt go home. 直到完成作業(yè)他才回家。應注意：在使用not until時，若not until放于句首，句子應部分倒裝。Not until he finished his homework，did he go home. 直到完成作業(yè)他才回家。四、when，if，until， before引導的狀語從句位置when , if和until引導的狀語從句放在主句前，也可放在主句后。但是放在主句前面時，須用逗號 ，隔開。而befor

13、e引導的狀語從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引導的狀語從句的時態(tài)用法在時間和條件狀語從句里，謂語動詞通常用現(xiàn)在時態(tài)表示將來的動作或狀態(tài)。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 hi

14、s father comes back today.n He doesnt go to bed until his father comes back every day.分析試題特點及做題思路考點：考連詞，考時態(tài)做題思路： 正確理解句子意思- 判斷語境提供的時態(tài)特點- 選擇正確的時態(tài)一、基礎題：1. When my mother returned last night, I _  a book. A. read   B. am reading   C. was reading  D. am going to read2. What

15、_ 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 u

16、p 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.

17、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. wa

18、nted        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 &#

19、160; 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

20、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 Shenzh

21、en _ 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      

22、0;   C. when          D. because20 . The volleyball match will be put off if it_         . A. will rain       B. rains        C. rained 

23、0;  D. is raining提高題：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.

24、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

25、 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. b

26、ecause10. 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

27、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        

28、   C. will       D. should go14. If he_ exercise, he_healthy.A. not; will                     B. isnt; wont beC. doesnt; will be      &

29、#160;       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          

30、 D. is coming; dont go難題：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, finishes  C. when, will finish   D. before, finishes.3 I _ her the answer if she _me.A. can tell, will ask   B. will tell, will ask  C. would tell, ask   D. will tell, asks4. It was quiet _ those big trucks started coming through the town.A. before B. after C. until D. unless 5. It seemed only seconds _ the boy finished washing his