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位置：从句可放在主句之前或之后，但是放在主句之前须有逗号隔开eg:如果我有足够的钱，我就去环游世界定义：if“如果,假如”它引导的句子表示某事发生所需的条件，即“在…条件下，某事才能发生”，在句子中充当状语，因此称之为条件状语从句。（If引导的条件状语从句表示假如有从句的动作发生，就会有主句动作的发生）IfIhaveenoughmoney,Iwilltravelaroundtheworld=IwilltravelaroundtheworldifIhaveenoughmoneyIfitrainstomorrow,Iwillstayathome.一、什么是条件状语从句？IfIgetuplate,Iwillbelateforschool.IfIdon’tfinishmyhomework,Iwon’tgotobed.Ifyoujointheband(乐队),youwillbefamous.主从句的时态？If条件句：条件句用于陈述语气，表示将来的可能性，能力，允诺，命令，要求，请求，建议时，假设的情况可能发生，其中if是“假如，如果”的意思。主句一般将来时，从句用一般现在时。构成条件从句主句时态If＋一般现在时主语＋shall/will+动词原形例句Ifhecomes,hewilltakeustothezoo.运用“主将从现”的原则。用法：1.如果主句是一般将来时，从句则用一般现在时。Ifitrains（从句），Iwillstayathome.I’llgowithyouifyoudon’twanttogoalone（从句）.2.如果主句含有must,may,can等情态动词，从句也要用一般现在时。Ifyoudrivetoofast,youmayhaveanaccident.Youmuststopifthetrafficisred.Ifyoufinishthehomework，youcangohome．如果你作业做完了就可以回家了。Ifyouwanttoloseweightyoumust/shouldeatlessbread.如果你想减肥，你必须少吃面包。•3.如果主句是祈使句，从句同样要用一般现在时。Don’tgoandplayfootballifyoudon’tfinishyourhomework.PleasecallmeifhecomesnextSunday.练一练：1。如果她早点儿起床，就有时间在家里吃早餐Ifshe________alittleearlier,she’llhavetimetoeatbreakfastathome.2。如果你参加聚会，你将会过得很开心。Ifyou____theparty,you_________agreattime.3。如果明天下雨，我们将不去野餐Ifit____tomorrow,we_______forapicnic.4。如果你经常听英文歌，你将会喜欢英语Ifyouoften_______Englishsongs,you______English.getsupjoinwillhaverainswon’tgolistentowilllike1.Ifhe____________(not,do)it,I___________(do)it.2.Ifyou____(be)lateforschool,myteacher________(be)angry.arewillbe3.Ifshe________(win)theprize,we_______(be)happy.winswillbe4.IfI_________(not,eat)somuch,I_________(get)thinner.5.Ifyou______(tell)them,they_____________(not,believe)you.don’teatwillgettellwon’tbelievedoesn’tdowilldo用所给单词的正确形式填空：6I_________(stay)athomeifit__________(rain).7.Ifit____________(not,rain),I_________(go)out.8.we__________(play)footballifitis_________(sun).9.Ifshe__________(become)astar,herparents____________(be)proudofher.10.He_________(watch)TVifhe______(be)free.willstayrainsdoesn’trainwillgowillplaysunnybecomeswillbewillwatchis2.If从句（一般现在时），主句（一般现在时）•表示科学常识、事实、经常性的动作或倾向自动会发生的事•1.Ifwaterisheated,itturnstosteam.•2.Ifpeopledon’tgetenoughsleep,theirthinkingabilityisreduced.•3.IfIneedahaircut,Iusuallygotothebarber’snearwhereIlive.•4.Peopleoftendon’tgooutonSundaysifitrains.1.as(so)longas….“只要…，就…”表示一种前提条件•You’llsucceedas(so)longas(ifonly)youtryhard.•只要你努力，你就会成功。拓展：那么，除了if之外，是否还有其他连词可以引导条件状语从句呢2．unless．除非；若不；如果不……；除非在……时候•1.Youwillfailtoarrivethereintimeunlessyoustartearlier．•如果你不早点动身，你就不能及时赶到那儿。2.Unlessbadweatherstopsme，Igoforawalkeverymorning．•除非天气不好，我每天早晨都要去散步。•3.Iwon‘tloanyouunlessyouareinextremeneedofmoney．•若不是你急需用钱，我不会借钱给你的。中考真题：（2011安徽）1.Iftherain_______(stop)tonight,wewillgotothecinema.（2012黑龙江）2.I’llbuyacomputerifI______(have)enougmoney.（2013内蒙古）3.You_________(notget)nervousifyou_____(do)enoughexercise.（2014浙江）4.Ifshe____(be)kindtome,I__________(notargue)withher.stopshavewon’tgetdoiswon’targue分析试题特点及做题思路：•1.考连词---做题思路：•分析句子---判断关系---选择正确的连词：•1.Youwon’tgetnervous_____youdoenoughexercise.•A.if,B,unlessC,whether•2._______youhurryup,youwillmisstheearlybus.•A.if,B,unlessC,whether分析试题特点及做题思路：2.Youmay______(pass)theexamifyou___(study)hard.2.考时态---做题思路：认字--判断语境提供的时态特点--选择正确的时态A.rain,stayB.rains,stayC.rains,willstayD.rain,willstay1.IfIt______(rain)tomorrow,I______(stay)athome.A.pass,studyB.willpass,studyC.pass,willstudyD.passes,studyIfI’mill,__________________.IwillseeadoctorLookandsayIfI’mlate,_________________.Iwillsaysorry条件状语从句在日常生中的应用：IfI’mhungry,Iwill______________.IfI’mtired,Iwill_____________.LookandsayeatsomefoodhavearestIfitrainstomorrow,I_____________________.willwatchTVathomeIfit_____________tomorrow,________________.I’llplaybasketballdoesn’trainif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，主将从现不一般；条件句表事实，主句常用现在时。Summary（小结）Ifwestudyharder,wewilldowellintheexams,Tryourbesttostudyharder.Homework.Finishtheexercisesintheworkbook.