If we pay much attention to the earth, well have a better world. 注意if还可以引导虚拟条件句，表示不可实现的条件，从句中多用一般过去时或过去完成时。
What would happen if there were no water 如果没有水会怎样 2.unless引导的条件状语从句You will fail in English unless you work hard. 3.as /so long as引导的条件状语从句So long as youre happy,i will be happy. 4.once引导的条件状语从句Once you begin,never stop. 提示在条件状语从句中，用一般现在时代替一般将来时，用一般过去时代替过去将来时。Father told me if i worked hard he would buy me a gift. if 条件状语从句的时态练习 二、用所给词的适当形式填空 1.If you ________feel tired, you _______________ have to have a rest. 2. Where _______ he _________see the film if he ________________have time 3. If there __________be fewer trees, there _______________ be more pollution. 4. He _____________dress more casually if he ________________ not work on weekends. 5. If Marcia _____________live alone, she ___________________ keep a pet parrot. 6. Lana ________________ buy a new dress if the old one ____________be out of style. 7.The twins ______________fight if they_______________argue. 8. I ____________have a bake sale if I _____________need money for education. 9. Peter _____________ send me a beautiful souvenir if he ________________tour Spain. 10. If Mr Green ___________say I am hard- working, my parents _________ feel glad. 11.I ____________go to the beach if it________________ not rain this week. 12. __________they __________ have a match if the P.E. teacher _____________be busy 13.He ____write a letter to his grandparents if he ____get his report card this week. 14. If she ____________get up late, she _____________ not catch the early bus. 15. Peter ________major in English if he ____pass the exams in Peking University. 15.如果他到的晚了会发生什么事情What _______________ if he _____________ late 16. 如果努力学习，你就会取得好成绩。
If you__________ _________, you ___________ good _____________. 17. 他如果看电视太久了，他的父母会不高兴。
If he _________ TV too much, his parents __________ __________ unhappy. 18. 如果我们为他组织生日聚会，大家都会来的。
Everyone ________________ if we _____________ a birthday party __________ him. 19. 如果明天不下雨，我会和你一起去公园的。
If it __________ __________ tomorrow, I ______________ go to the park _________ you. 20. 如果她睡过头了，就会旅游迟到的。
She;__________________________ the trip if she ___________________. 21. 如果他有空，他会帮助你的。
If he _________________, he _________________ you. 22. 如果Tom考试不及格，他就没有机会上高中了。
Tom _________have the ________to go to the ________high school if he ________ the exams. 23. 你如果抄同学的作业就不能学好各门功课。
You _______ _____ good at all the subjects if you ______ the other students’ homework. Ⅰ.单项选择（15分） 1.If you _____ to the party, you’ll have a great time. A. will go B. went C. go D. going 2. It will be a long time ____ Peter _____ his work. A. since, has finished B. after, finishes C. when, will finish D. before, finishes. 3. What will father _____ us from Japan A. take B. bring C. carry D. make 4. Weifang is famous ______ kites. A. for B. to C. on D. with 5． I ____ her the answer if she ____me. A. can tell, will ask B. will tell, will ask C. would tell, ask D. will tell, asks 6. – What are you going to do tomorrow --We’ll go to the library tomorrow if it ___. A. isn’t rain B. rain C. won’t rain D. doesn’t rain 7.Do you know when he will come back tomorrow --Sorry, I don’t know. When he ____ back, I’ll tell you. A. comes B. will come C. come D. may come 8. What will you do if you _____ to the old folk’s home visit A. go B. went C.going D. will go 9. If I eat ____ food, I’ll be very fat. A. too many B. many too C. too much D. much too 10. I’ll give the book to him if he ___ here next Sunday. A. will come B. comes C. is coming D. came 11. There ____an English film in our school tomorrow. A. is going to have B. will have C. is going to be D. has 12. Could you tell us where ____ A. will the next Olympic Games held B. the next Olympic Games will be held C. would the next Olympic Games be held D. the next Olympic Games would be held 13. When my mother returned last night, I ____ a book. A. read B. am reading C. was reading D. am going to read 14.What ____ you ____ when it began to rain A. do, do B. were, doing C. are, doing D. did, do 15. I’ll wake you up when he ____back. A. will B. is going to come C. comes D. come