if条件状语从句及其时态的用法

2) whether替换法：if引导宾语从句时，其意为“是否”，
通常可用whether替换，意义不变，而if引导条件状语从句
时不能用whether替换。因此，可用whether替换的是宾语从
句，不能替换的是条件从句。例如：
I want to know if you will go tomorrow. = I want to know whether you will go tomorrow. 注意：区分if的用法有着极为重要的意义，因为在条件状语 从句中，主句用将来时，从句用一般现在时；而在宾语从 句中，当主句是一般现在时，从句可用所需的任何时态， 主句是一般过去时，从句用过去的某种时态。
A. is going to have B. will be C. is going to play D. will play 10. I won’t go if it ____________ tomorrow. A. rain B. is raining C. rains D. will rain
5. 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. 6. 如果她睡过头了，就会误了开会的。 She _______ _______ _______ _______ the meeting if she _______ _______. 7. 如果他有空，他会帮助你的。 If he _______ _______, he _______ _______ you. 8. 如果Tom考试不及格，他就没有机会上高中了。 Tom _______ miss the chance to go to the high school if he _______ the exams. 9. 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.
一、概念
连词if的意思是“如果”，它引导的句子表示某事发生所 需要的条件，即“在……条件下某事才能发生”，在句子 中充当状语，因此我们称之为条件状语从句。在复合句中 连词if引导的句子为从句，被修饰的句子为主句。从句可 以放在主句后，也可以放在主句前，从句放在主句前时， 应用逗号将它与主句隔开。例如： We’ll go to the Great Wall if it doesn’t rain tomorrow. = If it doesn’t rain tomorrow, we’ll go to the Great Wall.
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 ________ (go) to 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) not 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.
三、完成句子
1.如果他迟到了，会发生什么事情？ What _______ ________ if he _______ late?
2. 如果努力学习，你就会取得好成绩。
If you_______ _______, you _______ _______ good _______. 3. 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. 4. 如果我们为他举办生日聚会，大家都会来的。 Everyone _______ _______ if we _______a birthday party _______ him.
5. I’ll give the book to him if he ____________ here next Sunday. A. will come B. comes C. is coming D. came 6. There ____________ an English film in our school tomorrow. A. is going to have B. will have C. is going to be D. has 7. I’ll wake you up when he ____________back. A. will B. is going to come C. comes D. come 8. The football match will be put off if it ____________. A. will rain B. rains C. rained D. is rained 9. There ____________ a basketball game this afternoon.
巩固练习
一、单项选择 1. If you ____________ to the party, you’ll have a great time. A. will go B. went C. go D. going 2. 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 3. — 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 4. — 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
if条件状语从句及其时态的用法
英国前首相撒切尔夫人（Margaret Thatcher）曾用if 条件句对男人和女人进行评价： In politics, if you want someone to make a speech, ask a man; if you want something done, ask a woman.
二、用法
• 1. 条件状语从句通常由连词if引导，意为“如果，假 如”，主句不能用be going to 表示将来，而应该用shall或 will。例如： If I’m free tomorrow, I’ll go with you. • 2. if引导的条件状语从句，主句用一般将来时，从句则 用一般现在时，即“主将从现”。例如： If it is sunny tomorrow, I’ll climb the hill.
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.
• 3. 正确区分if引导的条件状语从句和if引导的宾语从句： 在条件状语从句中，if表示“如果”；而在宾语从句中， if表示“是否”。可以用下面的方法区分： 1) 从句前置法：if引导的条件状语从句，可以放在主句之
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前并用逗号隔开，也可放在主句之后；而if引导的宾语从
句只能放在主句之后。因此如果把if放在主句之前，句子 通顺，意义不变，则是条件从句，否则是宾语从句。例如： He will help you if you ask him. = If you ask him, he will help you.