初中英语If引导的条件状语从句

1、初中英语一一if引导的条件状语从句在if引导的条件状语从句中，if和条件句位置灵活，可直接放在主句后面, 若if条件句放句首，从句后面要加逗号，和主句隔开。还要注意前后时态一致 原则.引导条件状语从句的连接词主要有：if（如果）、unless （除非）或as long as （只要）等。unless在意思上等于if.not。一、条件状语从句用法1、引导条件状语从句最常用的连词是if,由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。如：If you ask him, he will help you.如果你请他帮忙,他会帮你的。If you fail in the exam, you

2、will let him down.如果你考试不及格，你会让他失望的。另外方从句还表示不可实现的条件或根本不可能存在的条件,也就是 一种虚拟的条件或假设，从句多用一般过去时或过去完成时。如：If I were you, I would invite him to the party.如果我是你,我会邀请他参加聚会。2、unless = if.not.除非,若不,除非在的时候例如：Let's go out for a walk unless you are too tired.=lf you are not too tired, let*s go out for a walk. Unle

3、ss it rains, the game will be played.除非下雨，比赛将照常进行。二、时态问题在条件状语从句中，要注意“主将从现的规定，即主句用一般将来时，从句 用一般现在时表示将来时。例句：I will come to see you if I have time.我有时间，我就来看你。三 如果if条件句谈论的是重复发生和预示要发生的情景和事件，则主从句 大多用一般现在时态。如：If bears are in danger ,they attack people.误区提醒if既可以引导条件状语从句，表示“如果，也可以引导宾语从句，表达是 否。辨别它在这两种从句中的时态是我们

4、经常容易出错的地方。另外，if和 unless的用法也需注意。典型例题：-1 wonder if your wife to the party.-If your wife, so will mine。.A. will go, go B. will go, goes,will go D. will go, will go解析：第一句中if表示“是否，引导宾语从句，用将来时willgo；第二句如果你的妻子去，我的妻子也去，if引导条件状语从句，用一般现在时表示将来 时。your wife,单三人称主语，所以用goes。总结IF引导的一、表示将来可能发生的：(1) If sb does sth, s

5、b will do sth=sb will do sth if sb does sth主句一般将来时从句一般现在时(2)主句为祈使句或情态动词形式If sb does sth,please do sthIf sb does sth,sb may（情态动词） do sth二、表必然发生的If sb does sth,sb/sth does sth=sb/sth do sthif sb does sth主句一般现在时，从句一般现在时(相当于when引导的从句)Unless引导的sb will do sthunless sb does sthif sb does not do sth练习(not s

6、tudy) hard.(fail) in the exam if heyou(leave) now, you(be) late.(have) a barbecue unless it(rain).up, or you will miss the bus.(同义句转换)you don't hurry up, you catch the early bus.hard, or you'll miss fall behind.(同义句转换)you study hard, you fall behind.you don't put on your scarf, you'l

7、l catch cold.(同义句转换)Put on your scarf,you'll catch cold.don't know if it tomorrow.)(表是否，用将来时态)If it,1 won't go shopping. (rain)(表如果，用现在时态) want to know if he(come) tomorrow, if he(come), I(give) the massage to him.9. Please let us know if he(arrive) tomorrow.请告诉我们他明天是否会来Please let us kno

8、w if he(arrive) tomorrow.如果他明天来的话请告诉我们zm sure if he(go) to the party, he (have) a great time.the rain(stop) tonight, we will go to the cinema.II buy a computer if I(have) enough money.(not get) nervous if you(do ) enough exercise.she(be) kind to me , I(not argue) with her.you (pay) more attention to

9、 that, he (not get) injured.Li will be mad if we(break) the rules.17. If it(be) cloudy, they(not go) there by air.I say "Hello" when the foreigner(come) into the classroomII get better grades if he(study )hard.20. If you work really hard, you(be) famous and rich.if条件状语从句的时态练习一.在正确的答案下划一条线。

10、(will go/go/goes) to Europe if she (will pass/pass/passes) the exams .2. The graduates (will teach/teach/teaches) in the poor village if the Ministry of Education (will agree/ agree/agrees) soon.3. If a UFO (will land/land/lands) in front of mez I (will go/go/goes) in to look for the alien.4. If he

11、(will have/have/has) money, he (will bulid/build/builds) a science lab.'t wait for me if I (am/ will be) late.(won't/don't) go to the beach if it (will rain/rain /rains).7. I (will call/ call) you if he (will stay/stay /stays) at home.8. (Will / Do/ Does) he visit the museum if he (won&#

12、39;t / don't/ doesn't) get tired9. Where (will/ do/does) they live if they (will miss/ miss/ misses) the bus二、用所给词的适当形式填空you(feel) tired, you(have) to have a rest.3. If there(be) fewer trees, there( be) more pollution.)5. If Marcia (live) alone, she ( keep) a pet parrot.6. Lana( buy) a new d

13、ress if the old one(be) out of style.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.(go) to the beach if it( not rain) this week.12. they( ha

14、ve) a match if the . teacher(be) busy(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.I .单项选择（15分）you to the party, you'll have a great time. A

15、. will go B. went C. go D. going2. 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. make4. Weifang is famous kites. A. for B. to C. on D. with5. I her the answer if

16、she me.A. can tell, will ask B. will tell, will ask C. would tell, ask D. will tell, asks6. 一 What are you going to do tomorrow-Well go to the library tomorrow if it.A. isn't rain B. rain C. won't rain D. doesn't rain7. Do you know when he will come back tomorrow-Sorry, I don't know. When he back, Til tell you.A. comes B. will come C. come D. may come8. What will you do if you to