第1个回答 推荐于2017-11-26
条件状语从句 一、 条件状语从句通常由if（如果）, unless（除非），as long as（只要）引导。 例如：If it rains tomorrow, we won’t go to the park. 如果明天下雨，我们就不去公园了。 Unless weather stops me, I go for a walk every. 我每天都会去散步，除非遇上坏天气。 Our parents will be pleased with our performance as long as we try our best. 小试牛刀：1、只要我们竭尽全力，父母就会满意我们的表现。 Our parents will be pleased with our performance _____ _____ ______ we try our best. 2、如果人人为保护环境做出贡献，世界将会变得更美好。______ ______ ______ _____ _______ to protecting the environment, the world will become much more beautiful. 二、if引导的条件状语从句 （1）“if从句+祈使句”的句子。其实，if作为一个连词，主句也可以是其他形式的句子。 例如：If you want to go, please let me know. If the green light isn’t on, wait for a minute. (2)“祈使句 + and (or)+ 陈述句” 在意思上相当于一个带有条件状语从句的复合句。 注意：A. “祈使句 + and + 陈述句”可以转化为if引导的肯定条件状语从句，而且主语是第二人称。 B. “祈使句 + or + 陈述句”可以转化为if引导的否定条件状语从句，而且主语是第二人称。 例如：Study hard and you will pass the exam. =If you study hard, you will pass the exam. Hurry up, or you’ll be late. =If you don’t hurry up, you’ll be late. 考题 (2010重庆中考)Work hard，________ you may catch up with your classmates soon. A.or B.but C.and D.yet 思路解析：本句是“祈使句＋and”的句型，句意为“努力学习，你会很快赶上其他同学的”，and在句中表示承接关系，所以选C项。答案：C 黑色陷阱：本题的陷阱是句型，本句型区别于“祈使句＋or”，这个句型的含义是“……，不然的话/否则……”。 绿色通道：祈使句后面既可以加and，也可以加or，所以要全面分析句意，再作决定。 小试牛刀：用if连接下列句子 1、Go to bed early and you will have a good rest. 2、Hurry up, or you’ll miss the bus. 三、if从句与主句具有以下特点： 1．If从句中用一般现在时，表示未来的一种条件，从句中可以加时间状语。 e.g.If you can’t come tomorrow, we can hold the party a little later.明天你如果不能来，我们可迟一点举行宴会。If it doesn’t rain tomorrow, we’ll go to the Great Wall. 明天如果不下雨，我们就去长城。 2．当if表示未来的条件时，主句中用一般将来时，从句用一般现在时，即“主将从现”。表示如果某种条件存在，就有可能/不可能发生什么事情。 e.g.If you don’t get up early, you will be late for school.你如果不早点起床，上学就会迟到。 If I play games on it, it will go wrong. 如果我用它玩游戏，它就会坏掉。 3．if从句可放在主句前或主句后，从句置于主句前时，须用逗号与主句隔开，反之则不用逗号。 e.g.If it’s fine tomorrow, we can go out. 如果明天天气好，我们就能出去。 She will be happy if she joins the party. 如果她参加聚会她会很开心的。 I’ll ask the teacher for help if I don’t understand. 如果我不懂我会求助老师的。 三．注意if引导的条件状语从句和宾语从句的区别 if可以用来引导宾语从句也可以用来引导条件状语从句，主要是要弄清if引导从句的时态。if在引导宾语从句时，意为“是否”。要根据实际情况来确定时态，而if在引导条件状语从句时意为“如果，假设”，要用一般时代替将来时，即“主将从现”。 e.g.I want to know if he will come here tomorrow.我想知道他明天是否到这儿来。 （if在上句引导的是宾语从句，从句中有很明显的表将来的时间状语tomorrow，所以if从句要用一般将来时。） e.g.If it rains tomorrow, we’ll put off the sports meeting.如果明天下雨，我们就推迟运动会。 （if在上句引导的是条件状语从句，尽管从句中也有表将来时的时间状语tomorrow，从理论上讲也应该用一般将来时，但是在if引导的条件状语从句中要用一般现在时代替一般将来时，故从句谓语用rains而不用will rain. ） 二、典题分析 1、（2010上海）We will have no water to drink we don’t protect the earth. A. until B. before C. though D. if [答案]D．[解析] if 引导条件状语从句，表示 “如果”。意思是如果我们不保护地球，我们将会没有水喝。 2、（2011 重庆）We will plant trees tomorrow, and I don’t know Tom will come and join us. A. if B. which C. what D. where [答案]A．[解析] if 引导宾语从句，表示 “是否 ”。意思是我们明天将会去植树，但是我不知道Tom会不会去。 3、—Do you know if finished the work? —Not yet. If he , he will give me a call. A. he’s, will finish B. he’ll, finishes C. he’s , finishes D. he’ll , will finish [答案]C．[解析]问句的 if 引导宾语从句，表示 “是否 ”，从句要用陈述语序，从答句Not yet.中可以看出从句应该用现在完成时态，答句的if 引导状语从句，要遵循主将从现的规律。 练习 一、用if 连接下面的句子： 1、 You do not understand the article. Ask your teacher. 3 2、 You want to know more about it. Please call your teacher. 3、Tell him to make a phone call to me. He will come here tomorrow. 4、You want to go. Please tell me. 5、Look at our website. The camera does not work. 二、用所给的提示词组成一个if引导的条件状语从句。 1、 be tired, have a rest (Tom) 2、 not go to bed early, feel sleepy (you) 3、 become unhealthy, not eat vegetables (children) 4、 not listen to the teacher, not study well (I ) 5、 fall behind others in studying, spend too much time on the games (Da Wei) 三、单项选择： 1. You are sure to pass the exam ___ you study hard. A. if B. though C. that D. since 2. I'll go to see the film with you___I have time this evening. A. whether B. so C. if D. when 3. ___ you study harder, you'll never pass the final exam. A. If B. Until C. Unless D. Except 4．We’ll stay at home if it ______ this afternoon. A．rain B．rains C．to rain D．raining 5．We will go to the Great Wall if it ______tomorrow. A．won’t rain B．isn’t raining C．rained D．doesn’t rain 6．—I don’t know if he ______. —He will come if it ______. A．comes; won’t rain B．will come; doesn’t rain C．comes; doesn't rain D．will come; won’t rain 4 7．Do you know what time ______？ A．the train leave B．does the train leave C．will the train leave D．the train leaves 8．Do you think if______ an English film tomorrow night？ A．is there B．there is going to have C．there is going to be D．will there be 9．Will you please tell me ______？ A．where Pudong Airport is B．how far Pudong Airport was C．how can we get to Pudong Airport D．when was Pudong Airport built 10．—Mike wants to know if______ a picnic tomorrow. —Yes. But if it ______, we’ll visit the museum instead. A．you have; will rain B．you will have; will rain C．you will have; rains D．will you have; rains 11．—Why didn’t Nick come to school yesterday？ —______ he was ill. A．After B．Where C．When D．Because 12．This box is ______ heavy ______ I can’t carry it. A．too; to B．so; that C．very; that D．too; that 13．I don’t know ______ he still lives here. A．where B．what C．when D．whether 14. ---Do you know if he _______ to play basket ball 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 15. In the zoo if a child _____ into the water and can’t swim, the dolphins may come up ______ him. A. will fall; to help B. falls; to help C. will fall; help D. falls; helping 16.In the bookshop，a reader asked the shop keeper ___Who Moved My Cheese was an interesting book. A.that B.how C.what D.if 17、I want to know ________ you have a brother. A.if B.that C.those D.them 18、We will go hiking if it tomorrow. A.will be fine B.is fine C.be fine D. is gong to be fine 19、Maybe you if you make some bad friends. A.go wrong B. will go wrong C.going wrong D. is going to be wrong 20、—Do you know if finished the work? —Not yet. If he , he will give me a call. A. he’s, will finish B. he’ll, finishes C. he’s , finishes D. he’ll , will finish 5 答案：1-5 ACCBD 6-10 BDCAC 1-15 DBDCB 16-20、DABBC本回答被网友采纳