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。
eg：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.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.二、if引导的条件状语从句eg：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。
eg：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Work hard，________ you may catch up with your classmates soon.A.orB.butC.andD.yet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。
Eg:If you can’t come tomorrow, we can hold the party a little later.If it doesn’t rain tomorrow, we’ll go to the Great Wall.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。
eg.If you don’t get u p early, you will be late for school.If I play games on it, it will go wrong.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。
eg.If it’s fine tomorrow, we can go out.She will be happy if she joins the party.I’ll ask the teacher for help if I don’t understand.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”。
eg.I want to know if he will come here tomorrow.（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。
）eg.If it rains tomorrow, we’ll put off the sports meeting.（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、We will have no water to drink we don’t protect the earth.A. untilB. beforeC. thoughD. if2、We will plant trees tomorrow, and I don’t know Tom will come and join us.A. ifB. whichC. whatD. where3、—Do you know if finished the work?—Not yet. If he , he will give me a call.A. he’s, will finishB. he’ll, finishesC. he’s , finishesD. he’ll , will finish练习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 (DaWei)三、单项选择：1. You are sure to pass the exam ___ you study hard.A. ifB. thoughC. thatD. since2. I'll go to see the film with you___I have time this evening.A. whetherB. soC. ifD. when3. ___ you study harder, you'll never pass the final exam.A. IfB. UntilC. UnlessD. Except4．We’ll stay at home if it ______ this afternoon.A．rain B．rains C．to rain D．raining5．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 rain7．Do you know what time ______？A．the train leave B．does the train leaveC．will the train leave D．the train leaves8．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 be9．Will you please tell me ______？A．where Pudong Airport isB．how far Pudong Airport wasC．how can we get to Pudong AirportD．when was Pudong Airport built10．—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 rainC．you will have; rains D．will you have; rains11．—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; that13．I don’t know ______ he still lives here.A．where B．what C．when D．whether14. ---Do you know if he _______ to play basket ball with us?---I think he will come if he ______ free tomorrow.A. comes; isB. comes; will beC. will come; isD. will come; will be15. In the zoo if a child _____ into the water and can’t swim, the dolphins may come up ______ him.A. will fall; to helpB. falls; to helpC. will fall; helpD. falls; helping16.In the bookshop，a reader asked the shop keeper ___Who Moved My Cheese was an interesting book.A.thatB.howC.whatD.if17、I want to know ________ you have a brother.A.ifB.thatC.thoseD.them18、We will go hiking if it tomorrow.A.will be fineB.is fineC.be fineD. is gong to be fine19、Maybe you if you make some bad friends.A.go wrongB. will go wrongC.going wrongD. is going to be wrong20、—Do you know if finished the work?—Not yet. If he , he will give me a call.A. he’s, will finishB. he’ll, finishesC. he’s , finishesD. he’ll , will finish单选1. Don’t forget______ your homework.A. doingB. to doC. didD. does2. What about ______ at home?A. stayingB. stayC. to stayD. stays3. Our English teacher gave us ______ on how to learn English well.A. an adviceB. some adviceC. some advicesD. many advice4. Jack likes to ______ others but never writes to them.A. hearB. hear ofC. hear aboutD. hear from5. Some boys of Class 2 enjoy ______ music.A. listen toB. listens toC. listening toD. listened to6. Did Mary enjoy ______ at the party?A. herB. himselfC. oneselfD. herself7.. --Could you please _____ your watch to me?--OK. Here you are.A. showB. to showC. showingD.shows8. ---Do you still remember ______ me somewhere in Shanghai?---Yes, of course. Two years ago.A. to seeB. seeingC. seeD. saw9. ---I ______ it out in this way, but I failed.---Why ______ it in another way?A. tired to work; not try doingB. tired to work; not try to doC. tried working; not try to doD. try to work; not try doing10. How long does it ______ you to travel from Beijing to Shanghai?A. callB. takeC. makeD. use一、配对阅读。