2单元语法小专题.docx
单元语法小专题(GrainmarFocus)语法精讲if引导的条件状语从句条件状语从句通常由连词if引导，意为“假如；假如；倘如"，表示在某种条件下，很可能会发生某事或不发生某事。1if条件状语从句的位置在if引导的条件状语从句中，if条件句位置比较敏捷，可放在主句前面也可放在主句后面。若放在主句前，从句后面一般要用逗号和主句隔开。如：Ifhedoesn'tfeeltired,hewillvisitthemuseum.=Hewillvisitthemuseumifhedoesn'tfeeltired.假如他感觉不累»他就会去参观博物馆。2if条件状语从句的时态搭配(1)当主句用一般将来时，if引导的条件状语从句要用一般现在时。如：Ifitrainstomorrow»Iwon'tclimbthehi11s.假如明天下雨,我就不爬山。(2)当主句中含有can»may»must等情态动词时»if引导的条件状语从句要用一般现在时。如：WeCanWinthebaSketbangameifhejoinSUS.假如他力口入我们,我们就能赢这场篮球赛。(3)当主句是祈使句时，if引导的条件状语从句要用一般现在时。如：Helpyourmomwiththehouseworkifyoufinishyourhomeworkearly.假如你完成作业早,就帮你的妈妈做家务。if条件状语从句用法歌诀：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,表可能,主句多用将来时；条件句，表事实，主句常用现在时。3与其他句式之间的转换(1)借助“祈使句+and/or+一般将来时的句子”这一句型来转换。and在句意上表示顺承关系，or表示转折关系。如：Ifyougetupearly»you'llgetthereontime.=Getupearly,andyou'llgetthereontime.=Getupearly,oryouwon,tgetthereontime.早点起床，你就会准时到那里。(2)借助介词without或with来转换条件状语从句。如：Ifthereisnowater»fishwilldie.=FishwilldiewithoutWater.假如没有水»鱼就会死。Ifyouhelpme,llfinishtheworksoon.=Withyourhelp,llfinishtheworkSOOn.假如你帮助我，我就会早点完成工作。(3)ifnot引导的条件状语从句»可以借助连词unless来改写。如：Youwillbelateifyoudon,tgotherebybus.=Youwillbelateunlessyougotherebybus.假如你不乘公共汽车你就会迟到。语法精练I.用括号内所给单词的适当形式填空。1 Ifitrainstomorrow，Iwillstay(stay)athome.2 HewilltakeatriptoBeijingifheisn,t(benot)busynextweek.3 Pleasetell1.iJunaboutitifhecomes(come)back.4 Ifyoudon'twearyourschooluniformtotheparty，theteacherswon'tlet(notlet)youin.5 Shewon'tgo(notgo)shoppingwithherparentsifitsnowsthisafternoon.11.单项选择。（八）6.一Doyouknowwhenhewillcomebacktomorrow?Sorry，1don'tknow.Whenheback，I'lltellyou.AcomesB.willcomeCcomeD.maycome(D)7.MarywillgotoSanyaifsheafive-daytrip.AhaveB.hadCwillhaveD.has（八）8.Whatwillyoudoifyoutothepartywithoutinvitation?AgoB.wentC.goingD.willgo(D)9.IfIeattoomuchfood,Itoofat.AamB.wasC.willD.willbe(B)1O.11givethebooktohimifheherenextSunday.AwillcomeB.comesCiscomingD.camem.同义句转换，每空一词。11 Studyhard,oryouwon'tpasstheexam.Ifyoustudyhard，youWinDaSStheexam.12 Takeataxi»andyou'llcatchthetrain.Ifyoutakeataxi,you'llcatchthetrain.13 Ifyoudon,thelpme,Ican,tcatchupwiththeothers.14 can'tcatchupwiththeothersWithoUtyourhelp.15 Wewillbelateforthemeetingifwearen'tquick.WewillbelateforthemeetingUnleSSwearequick.16 Ifyouarelate，theteacherwillbeangry.Don'tbelate，ortheteacherwillbeangry.
