if 引导的从句的用法及练习题讲义 高考英语一轮语法总复习.docx

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1、if 引导的从句的用法及练习题（含答案） 高考英语语法总复习1. if 引导的宾语从句用在if引导的宾语从句中，if的含义是“是否”。在if引导的宾语从句中，从句用陈述语序，主句和从句之间的时态应当一致，即主句为一般现在时，从句用任一种时态；主句为一般过去时，从句则用过去时中的任一种时态。if引导的宾语从句，常放在动词ask, see, say, know和find out等后面。一般情况下，可与whether互换。例Nobody knows if it will rain tomorrow. 没有人知道明天是否下雨。Lucy asked if they had a sweater. 露西问他

2、们是否有毛衣。I dont know if/whether he will come here today. 我不知道他今天是否会来。Tom asked if/whether I had read the book. 汤姆问我是否看过这本书。辨if和whether引导宾语从句的区别：在动词不定式之前只能用whether。如：I cant decide whether to stay. 我不能决定是否留下。在whether.or not 的固定搭配中，只能用whether，不能用if。如：I want to know whether its good news or not. 我想知道这是否是好

3、消息。在介词后，只能用whether。如：Her father is worried about whether she will lose her job. 她的父亲担心她是否会失去工作。宾语从句放在句首表示强调时，只能用whether。如：Whether they can finish the work on time is still a problem. 他们是否能准时完成这项工作还是个问题。2. if 引导的条件状语从句（真实条件句）用在if引导的条件状语从句中，表示在某种条件下很可能发生时，就是真实条件句，通常从句用一般现在时，主句用将来时态或者情态动词+动词原形或者祈使句的形式。

4、1 if从句用一般现在时，主句用一般将来时例If he runs hell get there in time. 如果他跑的话，他就会及时赶到那儿。The cat will scratch you if you pull its tail. 如果你拉这只猫的尾巴，它就会抓你。2 if从句用一般现在时，主句用may/might/can+动词原形例If the fog gets thicker the plane may/might be diverted. 如果雾再大一些，飞机可能就会改在别的机场降落。If it stops snowing we can go out. 如果雪停了，我们就可以出

5、去。3 if从句用一般现在时，主句用must/should+动词原形例If you want to lose weight you must/should eat less bread. 如果你想减肥，就必须/应该少吃面包。4 if从句用一般现在时，主句用一般现在时例If you heat ice it turns to water.（也可用will turn）如果你给冰加热，它就会化成水。5 if从句用现在进行时，主句用一般将来时例If you are looking for Peter youll find him upstairs. 如果你是在找彼得，上楼就会找到他。6 if从句用现在完

6、成时，主句用一般将来时例If you have finished dinner Ill ask the waiter for the bill. 如果你吃完了，我就叫服务生来结账。3. If引导的条件状语从句（虚拟条件句）用表示的内容与现在事实相反，if从句用一般过去时，主句用“would/should/could/might+动词原形”；表示与过去事实相反，if从句用had+动词的过去分词，主句用would/should/could/might+have+动词的过去分词；表示对将来情况的主观推测，if从句用should+动词原形were to+动词原形，主句用would/should/cou

7、ld/might+动词原形。例If he should come here tomorrow, I would talk to him. 如果他明天来这儿的话，我就跟他谈谈。If I had taken his advice, I shouldnt/wouldnt/couldnt have made such a mistake. 如果我按照他的建议去做，我一定不会（不可能）犯这样的错误。If it should rain, the crops would/could/might be saved. 假如下雨，庄稼就一定（有可能）会得救。拓主句与从句时间不一致的用法If I had atten

8、ded the meeting yesterday, I would know what happened now. 如果我参加了昨天的会议，现在我就知道发生什么事了。省略if把had, should, were提前至句首，形成倒装结构Had it not been for him, I would be in hospital now. 要不是他，我现在就在医院里了。Should anyone call, tell him that Im not in. 有人打电话的话，告诉他我不在。Were it left to me to decide, I would choose to go to

9、college. 如果让我决定，我会选择去上大学。EXERCISE01. If I have enough money, I _ a school bus to help the poor children go to school.A. buyB. boughtC. will buyD. have bought02. What would happen if he _ back home?A. goB. goesC. wentD. going03. If I _ you, I would take an umbrella.A. amB. wereC. isD. be04. If more t

10、rees _ planted, our city will be more beautiful.A. wereB. areC. will beD. be05. If our government _ pay attention to the safety of food, our health _ in danger.A. isnt; isB. doesnt; will beC. wont; isD. isnt; will be06. I wont watch basketball matches _ James is playing. He pays much attention to te

11、amwork.A. unlessB. ifC. althoughD. since07. If you _ an English teacher, how _ you teach your students English?A. were; willB. were; wouldC. are; didD. are; would08. I apologize if I _ you, but I assure you it was unintentional.A. offendB. had offendedC. should have offendedD. might have offended09. If you hadnt taken such a long time to get dressed, wed _ there by now.A. beB. circlesC. is circlingD. be circling10. The sun rises in the east and sets in the west, so it seems as if the sun _ round the earth.A. were circlingB. circlesC. is circlingD. be circling答案01-05 CCBBB 06-10 ABBAA