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1、真实条件句和非真实条件句(虚拟语气)英语中的条件句分为真实条件句和非真实条件句。一、真实条件句: 表示现实情况中可能实现的情况。真实条件句中的谓语动词一般用一般现在时代替一般将来时，用一般过去式代替过去将来时。例如：If it rains tomorrow, I will stay at home.They said they would let us know if they heard any news about him.【详解】条件状语从句表示主句动作发生的条件，通常由if来引导，作“如果，那么”讲。详解例句时态如果主句用的是一般将来时，if 引导的条件状语从句常用一般现在时。如果主句
2、是祈使句，从句也常用一般现在时。如果主句含有情态动词，从句一般也用一般现在时。l I will visit my grandmother if I am free. l Lets go shopping if you are not busy. l You must be careful if you go swimming in the river.语序if引导的条件状语从句可以放在主句前面，常用逗号隔开；也可以放在主句的后面。If you dont hurry, you will be late. = You will be late if you dont hurry.转换“祈使句+an
3、d (or)+陈述句”在意义上相当于一个含有条件状语从句的复合句。“if+否定句”相当于“unless+肯定句”。Hurry up, or youll be late.= If you dont hurry up, youll be late.Dont come in if I dont call you. = Dont come in unless I call you.注：当连词if作“是否”讲时，if引导的从句的时态要根据具体情况而定。 ( ) 1. I hear Jack Chan will come to Laiwu next week. （2010山东莱芜）Really? _ he
4、 comes, my younger sister will be very happy.A. If B. Until C. Unless D. Before( ) 2. I dont know if it _ tomorrow. If it _, we wont go on a picnic. A. rains; rainsB. will rain; rains C. will rain; will rain( ) 3. We will have no water to drink _ we dont protect the earth. （2010上海）A. untilB. beforeC
5、. thoughD. if【巩固练习】. 单项选择( ) 1. We will stay at home if my aunt _ to visit us tomorrow.A. come B. comes C. will come D. is coming( ) 2. Do you know if he _ to play basketball with us?I think he will come if he _ free tomorrow.A. comes; is B. comes; will be C. will come; is D. will come; will be( ) 3
6、. You will keep healthy _ you do more exercise, such as running and swimming.A. if B. how C. before D. where. 根据汉语意思完成下列句子，每空一词。4. 如果明天不下雨的话，我们将去动物园。We will go to the zoo _ _ _ _ tomorrow. 5. 如果你完成了作业，我们就去下象棋。_ _ _ _ _, lets go to play chess.6. 如果人人都能保护环境，世界将会变得更美好。If everyone protects the environme
7、nt, the world _ _ _ _.二、非真实条件句: 也叫虚拟条件句，表示与现实情况相反的假设情况。主句和从句中的谓语动词都需要使用虚拟语气。在表示与事实相反的虚拟语气时，谓语动词有三种形式。其具体形式如下：时间概念 条件从句中的谓语动词 主句中的谓语动词与现在事实相反 did/were would(could/should/ might)+do与过去事实相反 had done/been would(could/should/might)+have done与将来事实相反 did/were would(could/should/ might)+ doshould do were to
8、 do注意：1. 上述主句的谓语中，would表示结果，might表示可能性，could表示能力、允许或可能性，should主要用于第一人称后。2. 条件从句的谓语动词为be时，不管其主语是单数还是复数通常用were。例如：If he were here now, we could ask him about it. (与现在事实相反)3. 混合条件句。当条件状语从句表示的行为与主句表示的行为所发生的时间不一致时，动词的形式要根据它所表示的时间做出相应的调整。例如：If he had followed the doctors advice then, he would be quite all
9、 right now. （从句表示过去时间，主句表示现在时间）4. (省if )倒装的虚拟条件句。 虚拟条件句的从句部分如果含有were, should或had, 可将if省略，把were, should或had 移到从句主语前形成倒装。例如：Had I seen him then, I would have been very happy.5. If it werent for和If it hadnt been for是两个很常用的虚拟语气句型，其意为“若不是（有），要不是有”。前者谈论现在的情况，后者谈论过去的情况。【即学即练】一、用动词的适当形式填空。1. What will you d
10、o if it _ (rain) tomorrow? We have to carry it on, since weve got everything ready.2. She told me that she would not go with me if it _ (rain) the next day.3. If I _ (be) you, I would plant some trees round the house.4. If I had been you then, I _ (not quarrel) with him.5. If the United States had b
11、uilt more homes for poor people in 1955，the housing problems now in some parts of this country _ (not be) so serious. 二、选择填空1. John went to the hospital alone. If he _ me about it, I would have gone with him.A. should tell B. tellsC. told D. had told2. If we _ the other road, we might have arrived h
12、ere in time for the meeting.A. take B. had takenC. took D. have taken3. If he _ my advice, he wouldnt have lost his job.A. followed B. should followC. had followed D. would follow4. Had I known about this computer program, a huge amount of time and energy _.A. would have been savedB. had been savedC
13、. will be saved D. was saved5. _ for the free tickets, I would not have gone to the films so often.A. If it is not B. Were it notC. Had it not been D. If they were not6. The weather has been very hot and dry. Yes. If it had rained even a drop, things would be much better now! And myvegetables _.A. wouldnt die B. didnt dieC. hadnt died D. wouldnt have died一、【中考链接】1-3 ABD【巩固练习】1-3 BCA 4. if it doesnt rain 5. If you finish your homework6. will become more beautiful二、Key: 1. rains 2. rained 3. were 4. shouldnt have quarrelled5. wouldnt be三、Key：1-5 CCDAD