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8Aunit7条件状语从句例句：Ifpeopleobeythetrafficrules,therewillbefeweraccidents.if引导的条件状语从句if:从属连词，意思是：“如果，假如，倘若”→从句→主句Therewillbefeweraccidentsifpeopleobeythetrafficrules.原句可改为：if引导的条件状语从句既可以放在句子前，也可以放在句子后。从句位于主句之前时，常用逗号将其与主句隔开。结构：→主句谓语中也可以含有情态动词，如：must,can,could,should等时态：if引导的条件状语从句，主句用一般将来时（will）,从句用一般现在时。例句：Ifpeopleobeythetrafficrules,therewillbefeweraccidents.→主句谓语中也可以用hadbetter(not)do,提建议例句：如果交通指示灯是红的，你必须停下来等一等。eg:Ifthetrafficlightsarered,youmuststopandwait.例句：如果你想减肥，你最好锻炼。eg:Ifyouwanttoloseweight,youhadbettertakesomeexercise.[句式结构及时态]：Ifanearthquakehappens,manybuildingswillfalldown.Ifafirehappens,don’tbenervous.Ifacaraccidenthappenstoyou,whatshouldyoudo?从句:从句：一般现在时从句：一般现在时主句：主句：祈使句主句：含情态动词can/could/must/should等一般现在时一般将来时(will)Revision[句式结构]：[时态]:祈使句一般将来时(will)一般现在时,情态动词(can/must/should/…)SummaryIf从句，+主句./主句+从句3.口诀:___________条件状语从句：If2.if从句用___________，主句也用__________，表示客观事实或习惯。主现从现1.如果我把玻璃杯扔掉，它就会摔碎。IfI_______aglass,it________.一般现在时一般现在时dropbreaks②Unless如果不，除非•条件状语从句:unless从句遵循if从句主将从现和主现从现的情况。要领:unless=if…not1.如果明天不下雨，我们就去远足。Ifit__________________,wewillgohiking.=Wewillgohiking__________________2.如果你不把肉存放在冰箱里，它就会变坏。Ifyou__________________inthefridge,it_________.=_______________________inthefridge,it_________.Unless=If…notunlessitrainstomorrow.doesn’traintomorrowdon’tkeepthemeatUnlessyoukeepthemeatgoesbadgoesbadUnless=If…not3.除非天下雨，他通常是走路去上学。Heusually_____________onfootifit___________.=_____________,heusually_____________onfoot.4.如果你现在不走，你就赶不上火车了。Ifyou________________,you_________thetrain.=___________________,you_________thetrain.goestoschooldon’tleavenowUnlessitrainsgoestoschoolUnlessyouleavenowwon’tcatchwon’tcatchdoesn’trainSummary•条件状语从句:•if从句•unless从句主将从现主现从现•时态口诀:将来客观事实习惯用括号内所给词的正确形式填空：1.Ifhedoesn’tgototheparty,I_______,either.2.Ifshe______(be)kindtome,I___________(notargue)withher.3.Iwanttoknowifhe_________(come)tomorrow,ifhe_______(come),Iwillgivethemessagetohim.won’tiswon’targuewillcomecomes7.Ifyou(find/found)thegasleaksout,(open/opening)thewindowsassoonaspossible.8.Ifthere(willbe/was/is)afire,thehouse(willbe/was/is)beinruins(化为废墟).二、用括号内所给词的正确形式填空：1.Ifhedoesn’tgototheparty,I_______,either.2.Ifshe______(be)kindtome,I___________(notargue)withher.3.Iwanttoknowifhe_________(come)tomorrow,ifhe_______(come),Iwillgivethemessagetohim.won’tiswon’targuewillcomecomes4.Where____he______(see)thefilmifhe_________(have)time?5.Ifthere_______(be)fewertrees,there__________(be)morepollution.6.Ifanearthquake__________(happen)inShantou,canyouimaginewhat___________(happen)?7.Ifyou_______(have)acaraccident,youshouldcallyourparentsoryourfriends.8.Ifyou_____(stay)athomealone,what_____you_____(do)?willseehasarewillbehappenswillhappenhavestaywilldoif的反义词：if...not...=unless,意思是：“如果不，除非”Iwon’tgothereunlessIhearfromyou.(同义)Iwon’tgothere_____I_____hearfromyou.ifdon’tIwon’tgotothepartyifIamnotinvited.(同义句)Iwon’tgototheparty_____Iaminvited.unless变换：1.有if引导的条件状语从句的复合句中，当主句和从句的主语均为you时，可转换为“祈使句，and+简单句”或“祈使句，or+简单句”Youcanpasstheexamifyouworkhard.----------------，andyouwillpasstheexam.Ifyoudon'thurryup,youwillbelateagain.Hurryup,------youwillbelateagain.Workhardor2.借助介词with或without来转换。例如:Ifyouhelpme,I’llfinishmyjobsoon.------------------,I’llfinishmyjobsoon.如果你帮我，我将很快完成我的工作。Ifthereisnowater,fishmaydie.Fishmaydie------------------.如果没有水，鱼可能会死。Withyourhelpwithoutwater•注意事项•1.在if引导的条件状语从句中，当主句是一般将来时时，不能够使用begoingto结构，而要用will。•例如：I’llhelpyouwithyourEnglishifIamfreetomorrow.如果明天我有空，我会帮你学英语。•2.在if引导的条件状语从句中不能够使用some，而要用any。•例如：Ifyouhaveanyquestionstoask,pleasecometomyoffice.如果你有问题要问的话，请到我办公室来。2.条件状语从句引导状语从句的连接词有:If,unless,aslongas,incase,providedthat,onconditionthatIf---如果Ifyoudon’thurryup,youwillmisstheplane.Ifitsnowstomorrow,theflightwillbecanceled.Ifyouleaveat6o’clocktomorrowmorning,you’dbettergettobednow.Unless---如果不,除非=ifnotWecan’tgetthereontimeunlesswebooktheearliestflight=Wecannotgetthereontimeifwedon’tbooktheearliestflight.Don’ttroubletroubleunlesstroubletroublesyou.Hewillnotjoinusunlesshechangeshismind.Aslongas---只要Wewillsucceedaslongaswekeepontrying.Youcan’tplaygamesaslongasyouremembertherules.Amanisnotoldaslongasheisseekingsomething.As(so)faras---据……所知AsfarasIknow,hespeaksEnglishverywell.As/SofarasIknow,heisanexpertonDNA.Incase---假使,如果Theplanecannottakeoffincaseitrains.Sendusamessageincaseyouhaveanydifficulty.Providedthat如果,有时省略thatTheplanewillbeingoodconditionprovidedthatitistakencareofcarefully.Youcanbecomeastewardessprovidedthatyouareingoodshapeandyouhavegotthepropereducation.Onconditionthat---条件是…Hesaidthathewouldcometothemeetingonconditionthatnooneaskedhimtospeak.ThemotherpromisedtothesontobuyhimatoyairplaneonconditionthathepasseshisEnglishtest.