if条件状语从句

if条件状语从句

If 引导的条件状语从句

If 引导的条件状语从句表示“如果… , 假如…”，表示在某种条件下某事可能发生。含有if引导的条件状语从句的复合句由主句和从句构成。If引导的是完整的句子，一定要有主语，称为从句，另一个句子称为主句。

句子结构：1. 祈使句/ 主句（will do ）/ 主句（can / must / should 等+do）+if条件状语从句

2. if条件状语从句, + 祈使句/ 主句（will do ）/ 主句（can / must / should 等+do）

1. Drop in on me if you have time . = If you have time , drop in on me .

2. I will help you do housework if I finish my homework earlier .

= if I finish my homework earlier , I will help you do housework .

3. Y ou must study hard if you want to pass the exam . = If you want to pass the exam , you must study hard .

特别注意：

（1）上述情况下，条件状语从句必须用一般现在时态表示将来动作。不可用一般将来时。

（2）if条件句和”祈使句+and / or+简单句”句型的转换

Hurry up , or you’ll be late .= If you don’t h urry up, you will be late .

Go straight ahead , and you will find the post office . = If you go straight ahead , you will find the post office .

(3) unless 引导条件状语从句，可以和if转换。unless（如果不，除非）= if … not …

I won’t go to her birthday party unless she invites me .

专项练习：

1. ______ my watch if your watch ______ . A. Look at ; isn’t work

B. Look at ; doesn’t work

C. Look ; works

D. Look ; doesn’t work

2. Please get up early _____ you want to catch the first bus .

A. or

B. because

C. and

D. if

3. ______ to lock the door if you _____ the last one to leave .

A. Forget ; are

B. Don’t forget ; will be

C. Forget ; will be

D. Don’t forget ; are

4. If you _____ to stay healthy , ____ some exercise every day .

A. want ; do

B. wants ; does

C. will want ; do

D. will want ; does

5. _____ your mother the truth , if you don’t like it .A. T ell B. To tell C. Telling D. Tells

6. If you have something important to tell us , _____ it right now ! A. speak B. talk C. tell D. say

7. If you ______ to the music , buy a CD . A. will listen B. listen

C. listening

D. listened

8. Be careful if you ______ want to make mistakes . A. won’t

B. don’t

C. didn’t

D. not

9. If you ____ a chance to study in a foreign country , just take it .A. getting B. had got C. will get D. get

10. All of us will be happy _____ you can come with us . A, while B. if C. but D. or

11. If Mr. Smith ____back , please let me know . A. will come

B. comes

C. come

D. had come

12. I am waiting for my friend. _______ , I’ll swim alone .

A. If he doesn’t come

B. If he won’t come

C. If he will come

D. If he is coming

13. I’ll go to the zoo if it _____ tomorrow .A. doesn’t rain B. will rain C. rains D. won’t come

14. If you___ another programme , ___ this button .

A. choose ; press

B. chose ; press

C. chose ; to press

D. choose ; pressing

15. Hurry up , _____ you’ll miss the last bus .

A. or

B. if

C. so

D. then

16. I won’t finish washing the dishes before 7:00 , ____ you _____ help me .

A. unless ; /

B. if ; don’t

C. when ; /

D. A or B

17. --- ______ if he leaves school this afternoon ? ---- The teacher will punish him .

A. What will happen

B. What happens

C. What happened