1、1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 wont 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 paren
2、ts 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 isnt on,
3、 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 youll be late. =If you dont hur
4、ry up, youll 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
5、 early and you will have a good rest. 2、Hurry up, or youll miss the bus.三、if 从句与主句具有以下特点：1If 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 cant 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。2If it doesnt rain tomorrow, well 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
6、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 dont 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。3if 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 its fine tomorrow, we can go out. 如果明天天气好，我们就能出去。She will be happy
7、if she joins the party. 如果她参加聚会她会很开心的。Ill ask the teacher for help if I dont 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.
8、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, well 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
9、 water to drink we dont 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 dont 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
10、 you know if finished the work? Not yet. If he , he will give me a call.A. hes, will finish B. hell, finishes C. hes , finishes D. hell , 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。3练习一、用 if 连接下面的句子：1、 You do not understand the article. Ask
11、your teacher.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,
12、 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. since2. Ill go to see t
13、he film with you_I have time this evening.A. whether B. so C. if D. when3. _ you study harder, youll never pass the final exam.A. If B. Until C. Unless D. Except4Well stay at home if it _ this afternoon.Arain Brains Cto rain Draining 5We will go to the Great Wall if it _tomorrow. Awont rain Bisnt ra
14、ining Crained Ddoesnt rain 46I dont know if he _.He will come if it _.Acomes; wont rain Bwill come; doesnt rain Ccomes; doesnt rain Dwill come; wont rain 7Do you know what time _？Athe train leave Bdoes the train leave Cwill the train leave Dthe train leaves 8Do you think if_ an English film tomorrow
15、 night？Ais there Bthere is going to have Cthere is going to be Dwill there be 9Will you please tell me _？Awhere Pudong Airport is Bhow far Pudong Airport was Chow can we get to Pudong Airport Dwhen was Pudong Airport built 10Mike wants to know if_ a picnic tomorrow.Yes. But if it _, well visit the m
16、useum instead. Ayou have; will rain Byou will have; will rain Cyou will have; rains Dwill you have; rains 11Why didnt Nick come to school yesterday？_ he was ill. AAfter BWhere CWhen DBecause 12This box is _ heavy _ I cant carry it.Atoo; to Bso; that Cvery; that Dtoo; that 13I dont know _ he still li
17、ves here.Awhere Bwhat Cwhen Dwhether 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 be15. In the zoo if a child _ into the water and cant swim, the dolphins may come up _ him.A. will
18、fall; to help B. falls; to help C. will fall; help D. falls; helping16.In the bookshop，a reader asked the shop keeper _ Who Moved My Cheese was an interesting book.A.that B.how C.what D.if17、I want to know _ you have a brother.A.if B.that C.those D.them18、We will go hiking if it tomorrow.A.will be f
19、ine B.is fine C.be fine D. is gong to be fine19、Maybe you if you make some bad friends.5A.go wrong B. will go wrong C.going wrong D. is going to be wrong20、Do you know if finished the work? Not yet. If he , he will give me a call.A. hes, will finish B. hell, finishes C. hes , finishes D. hell , will finish答案：1-5 ACCBD 6-10 BDCAC 1-15 DBDCB16-20、DABBC
