If-用法汇总及练习

if用法汇总1、主将从现（主句为一般将来时 ,从句为一般现在时）； eg:if it rains(从句 ) ,i will stay at home（主句） .=i will stay at home if it rains.2、主句含有情态动词（must、may、can etc.）从句为一般现在时； eg:if you drive too fast ,you may have an accident.=you may have an accident if you drive too fast 3、主句为祈使句 ,从句要用一般现在时态；eg:dont play computer games if you dont finish your homework.4、是否 =whetherask if he is at home.i wonder if she is ill. 5、虚拟语气eg:ifi were a bird ,i would fly in the sky.（事实我不可能是鸟）时态：可以表示过去， 现在和将来的情况， 它的基本特点是时态退后. a.同现在事实相反的假设从句用一般过去时should( would) +动词原形if they were here,they would help you. b.表示于过去事实相反的假设从句用过去完成时should(would) have+ 过去分词if she had worked harder,she would have succeeded.ifmy lawyer had been here last saturday,he would have prevented me from going.c.表示对将来的假想一般过去时，were+ to do，从句：主 + should/would/could/might+v原形should+ v原形，if you succeeded,everything would be all right.if you were to succeed,everything would be all right. if you should succeed,everything would be all right.单项练习（每个必须让学生翻译）1. if i where he lived, i a note to him.a. know, would have sentb. had known, would have sentc. know, would sendd. knew, would have sent2. mary is ill today. if she , she absent from school.a. were not ill; wouldn t beb. had been ill; wouldn t have beenc. had been ill; should have beend. hadnt been ill; could be3. he acted as if he everything in the world.a. knewb. knowsc. has knownd. wont know4. if you had enough money, what ?a. will you buyb. would you buyc. would you have boughtd. will you have bought5. if mr. young with justice, he such a wrong thing.a. were treated; wouldn t dob. had been treated; wouldnt have donec. were treated; wouldn t have doned. had been treated; wouldnt do6. what if there no light during the day?a. will happen; wasb. would happen; isc. happens; wered. would happen; were7. the spokesman acted that wayas ifhe anythingabout the accident but actually he did.a. doesnt hearb. didnt hearc. havent heardd. hadnt heard8. ifit not forthe factthat you illnow, iwouldsurely punish you.a. is; areb. were; werec. were; ared. was; were9. many chinese movie stars now have given up their chinese nationality.if i were them,i that.a. shouldn t dob. didnt doc. hadnt doned. won t do10. i want to get back by 5 oclock if .a. likelyb. canc. possibled. probable11. it seems as if it already summer now but it is only february.a. isb. wasc. wered. had been12. if henry had not pulled his cap low over his brow, he by the police.a. might be recognizedb. might have been recognizedc. would have recognizedd. was to have been recognized13. there is a ring at the door. that be the postman, i suppose.a. willb. wouldc. is going tod. was going to14. look at the dark clouds there be a storm.a. willb. must have beenc. is going tod. would15. why are you taking the pictures down? i the wall.a. paintb. have just paintedc. am going to paintd. will have painted16. can i stay at home tomorrow? yes, you can if it .a. will snowb. is going to snowc. snowsd. snowed17. i dont know if he this afternoon. but if he , i will tell you.a. will come; will do;b. comes; will doc. will come; doesd. comes; does18. i thought i asked you to fix the radio. oh, i m sorry. i it right away.a. am to dob. will doc. was about to dod. am going to do19. the wtocan tliveup toits name itdoes not include a country that is home to one fifth of mankind.a. as long asb. whetherc. ifd. even though20. ask him to ring me up if you him.a. seeb. sawc. would seed. will see21. its so late. i dont think he come.a. wouldb. shouldc. is going tod. shall22. if people polluting the air, animals and plants will die soon.a. dont stopb. didnt stopc. shall not stopd. haven t stopped23. if you an interesting day out, the science museum.a. want; visitingb. want; visitc. want to; visitd. wanting; visit24. if the pure water is heated to 100 centigrade degrees, it boil.a. is going tob. willc. wouldd. is to25. is a dictionary available, so, where?a. ifb. if isc. and ifd. and if is15 baabb610 ddcac11 15 cbacc16 20 ccbca21 25 cabbc最后一练1. if you to the party, you ll have a great timeb. .aw. ewniltl gco . god. going2. it will be a long time peter his work.a. since, has finishedb. after, finishesc. when, will finishd. before, finishes.3. what will father us from japan? a. takeb. bringc. carryd. make4. weifang is famous kites. a. forb. toc. ond. with5. i her the answer if sheme.a. can tell, will askb. will tell, will askc. would tell, askd. will tell, asks6. what are you going to do tomorrow?-we ll go to the library tomorrow if it.a. isn t rabin. rainc. won t raind. 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. comesb. will comec. comed. may come8. what will you do if you to the old folk s home visit?a. gob. wentc.goingd. will go9. if i eat _ food, i ll be very fat.a. too manyb. many tooc. too muchd. much too10. i ll give the book to him if he here next sunday.a. will comeb. comesc. is comingd. came11. there an english film in our school tomorrow.a. is going to haveb. will havec. is going to bed. has12. could you tell us where ？a. will the next olympic games heldb. the next olympic games will be heldc. would the next olympic games be heldd. the next olympic games would be held13. when my m