条件句从句主句真实一般现在时一般将来时情态动词+动原祈使句非真实一般过去时be动词用（were）would/could+动原初中英语――条件状语从句（讲解&练习）Ⅰ条件状语从句的定义Ⅱ条件状语从句的引导词1.if引导的条件状语从句：表示在某种条件下某事很可能发生。
If we pay much attention to the earth, we'll have a better world.如果我们多关爱地球，就会拥有一个更美好的世界If it rains tomorrow, what shall we do?如果明天下雨，我们怎么办？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，unless的意思是如果不，除非。
可与if...not互换。
You will fail in English unless you work hard.你英语考试会不及格的，除非你更加努力。
3.as /so long as引导的条件状语从句：as /so long as意思是“只要”So long as you're happy,i will be happy.只要你高兴，我就高兴。
Ⅲ条件状语从句的种类Ⅳ条件状语从句的时态原则用法例句①主句为一般将来时态，if从句用一般现在时态（即主将从现）。
We will stay at home if it rains tomorrow.如果明天下雨，我将要呆在家。
②主句中含有情态动词，if从句用一般现在时态。
If you finish your homework, you can go home now.如果你做完了作业，你现在可以回家了。
③主句为祈使句，if从句用一般现在时态。
Don’t jump into the river if you feel very hot. 如果你感到很热，不要跳入河里。
④主句为过去将来时，if从句用一般过去时态（如果涉及到be动词，一律都用were）。
此时，表达的是和现实相反的推测，用虚拟语气。
If I were you, I wouldn’t do it like that.如果我是你，我就不会那么做的。
If you gave me some money, I would be very happy. 如果你给我一些钱，我就会很高兴的。
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.(2)“祈使句 + and (or)+ 陈述句”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：1.Study hard and you will pass the exam.=If you study hard, you will pass the exam.2. 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.注意：学习" if " 引导的条件状语从句的用法,现在总结一下:if 条件句不一般,几个要点记心间;条件句,放在前, 逗号要放句中间。
条件句表真实，主将从现要遵从；条件句非真实，虚拟语气用到位。
【边学边做】用括号内所给词的正确形式填空。
1. What will you buy if you ________（have）a lot of money?2. If it ________（not snow）tomorrow, we will feel unhappy.3. You mustn’t go to school if you ________（be）still in bed.4. If he _______（be）at home at that time, he would know it.5. Please show me the way if you ________（know）it.6. You will hurt your teeth if you ________（eat）too much candy.7. If you gave me a toy car, I _________（be）very happy.8. I would get the prize if I _________（work）hard.练习Ⅰ.单项选择（）1.If you _____ to the party, you’ll have a great time.A. will goB. wentC. goD. going（）2. I ____ her the answer if she ____me.A. can tell, will askB. will tell, will askC. would tell, askD. will tell, asks（）3. – What are you going to do tomorrow?--We’ll go to the library tomorrow if it ___.A. isn’t rainB. rainC. won’t rainD. doesn’t rain（）4. What will you do if you _____ to the old folk’s home?A. goB. wentC. goingD. will go（）5．I’ll give the book to him if he ___ here next Sunday.A. will comeB. comesC. is comingD. cameⅡ.用所给词的适当形式填空6..If you ________(feel) tired, you _______________ (have) to have a rest.7. Where _______ he _______(see) the film if he _____________(have) time?8. If there _______(be) fewer trees, there ____________( be) more pollution.9. If Marcia ________(live) alone, she ________________( keep) a pet parrot.11. Lana _________( buy) a new dress if the old one ________(be) out of style.12.The twins ______________(fight) if they_______________(argue).13. I _______(have) a bake sale if I __________(need) money for education.14. Peter _______( send) me a beautiful souvenir if he ________(tour) Spain.15. I ____________(go) to the beach if it_________ ( not rain) this week.17. _____they _______( have) a match if the P.E. teacher __________(be) busy?18. If she ____________(get) up late, she _________ ( not catch) the early bus.Ⅲ.翻译下列句子19..如果他到的晚了会发生什么事情？What _______________ if he _____________ late?20. 如果努力学习，你就会取得好成绩。
If you__________ _________, you good marks.21. 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.22. 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.23. 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.24. 如果她睡过头了，就会旅游迟到的。
She;__________________________ the trip if she ___________________.25. 如果他有空，他会帮助你的。
If he _________________, he _________________ you.26. 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.。