if条件句

Unit6GrammarIf--clausesif条件句表示的是事实时Oilfloatsifyoupouritonwater.Youmustseethedoctorifyouareill.在这种用法里，可用when代替if。if条件句谈论将来的情况IfIhaveenoughtime,Iwillcometoseeyou.Ifit'ssunnytomorrow,wewillgotohaveapicnic.Whatwillyoudoifyoufindapandaindanger?如果if条件从句放在句首，从句后面用逗号。IfIcanaffordit,Iwillbuyavilla.Ifyoulike,youcanleavenow.若主句在前、if条件句在后，则主从句之间无须用逗号分开。IwillbuyavillaifIcanaffordit.Youcanleavenowifyoulike.一般情况下，if从句中的动词用一般现在时表示将来，主句动词则用将来时。Ifyougetherebeforeeight,wecancatchtheearlytrain.IfIhaveenoughtimenextweek,Iwillcometoseeyou.有时if从句中的动词也可以用现在进行时或现在完成时。IfwearebuildingspaceshipsfortravellingtoMars,we'llhavetousesolarenergy.Ifyouhaven'tfinishedyourhomeworkby7:00,youcannotwatchthedramaonTV.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。if后的从句可以有省略形式在if引导的条件从句中，如果从句的主语是it，或与主句的主语相同，且在谓语中含有be动词时，常省略从句主语和be。If(itis)necessary,ringmeathome.If(itis)necessary,gotherebyair.Hewillcomeif(heis)asked.If(hewas)givenmoreattentionto,theboycouldhaveturnedoutbetter.祈使句和if条件句的转换“祈使句＋and＋简单句”结构可转换为含if条件状语从句的复合句。Workhard,andyou’lllearnwell．=Ifyouworkhard,you’lllearnwell．“祈使句＋or＋简单句”结构可转换为含if条件状语从句的复合句，从句中的谓语须用其否定形式。Hurryup,orwe’llmisstheearlybus.=Ifwedon’thurryup,we’llmisstheearlybus.TranslatethesentencesintoEnglish.1.如果天气晴朗，他们要发射宇宙飞船。Iftheweather______,they________thespaceship.isclearwilllaunch2.如果一颗人造卫星发生故障，宇航员要乘太空漫步去修复它。Ifasatellite________inspace,anastronaut_______________torepairit.isbrokenwilltakeaspacewalk3.如果你在太空，地球看上去是蓝色。Ifyou_________,Earth_______.areinspacelooksblue4.如果宇航员在月球行走，因为没有空气，他要穿着一件宇航服。Ifanastronaut______________,he_____________becausethereisnoair.walksontheMoonwearsaspacesuit5.如果宇航员想在月球上行走更远，他要开一辆月球车。Iftheastronaut____________________,he_______________.wantstotravelfarontheMoondrivesaMoonbuggy6.如果一切顺利，宇航员们会安全返回地球。goeswellIfeverything__________,theastronauts_________________.willlandsafelybackonEarthColumnAColumnB1.IfhespeaksEnglishwithaBritishaccent2.Ifyoulikeyellowroses3.Iftheunionworkersdon’tacceptthiscontract4.IfAmybuysablackdress5.IfMr.Edisontakesaplanea.IamsureyouwouldlikethePeacerose.b.therewillbeastrikeonFriday.c.he’llbehometonight.d.she’llneedsomeblackshoes,too.e.it’sbecausehestudiedinEngland.Matchthetwosentences.1.Runfast,oryou’llbelateforschool._______you______________fast,you’llbelateforschool.2.Youcanbuythedictionaryifyoutakeenoughmoneywithyou.Takeenoughmoneywithyou,_________________buythedictionary.3.Ifthereisnoair,noneofuscanlive.Noneofuscanlive________________.Exchangethesentences.Ifdon’trunandyoucanwithoutair1).如果你吃坏食物，你可能会生病。Ifyoueatbadfood,youmaybeill.2).如果你有时间，请跟我来。Comewithmeifyouhavetime.3).如果有时间我们会来看你。Wewillcometoseeyouifwehavetime.TranslatethesentencesintoEnglish.Otherwordsandexpressionstointroduceconditionalclausesaslongas引导的条件状语从句Theycansurviveonlyaslongastheywearspacesuits,because95percentoftheatmosphereiscarbondioxide.I'lllendyouthemoneyaslongasyoureturnitwithinsixmonths.unless引导的条件状语从句Unlesstheycangetaloan,theyaredefinitelynotgoingtobuyit.Unlessyoufeelsick,donottakethesepills.在条件状语从句中，unless的含义相当于if...not，在句型转换中要特别注意。Unlesswestopairpollution,wewillnolongerbeabletobreathetheaironEarth.=Ifwedonotstopairpollution,wewillnolongerbeabletobreathetheaironEarth.onconditionthat可引出条件从句，一般译为“只要；以...为条件”。Youcanusethebicycleonconditionthatyoureturnittomorrow.Ishallgiveyouthebookonconditionthatyoureturnitnolaterthantomorrow.supposing可用作连词，表示“假如”，引导条件句。Supposingthatheasksyou,willyougo?Supposinghedoesnotcome,shallwegowithouthim?Supposinghecan’tcome,whowilldothework?providedconj.假如,除非,以……为条件Provided(that)thereisnoopposition,weshallholdthemeetinghere.Wewillbetherebefore10,providedwedon’twastetime.1.(2013江西)Shesaysthatshe’llhavetoclosetheshop________businessimproves.A.ifB.unlessC.afterD.when解析：考查状语从句。根据句意“如果生意没有好转，她就只得关店铺”,unless=if…not(如果不)，故答案选B。高考真题B2.(2013重庆)25.______wehaveenoughevidence.wecan'twinthecase.A.OnceB.AslongasC.UnlessD.Since解析：考查状语从句。根据句意“除非我们有足够的证据，否则这个案子我们不能取胜”，可知选C。C3.Ihaveatightbudgetforthetrip,soI’mnotgoingtofly______theairlineslowerticketprices.（2012上海）A.onceB.ifC.afterD.unless解析：考查连词意义辨析。句意：我的旅行预算比较紧张，所以除非机票降价否则我是不会乘飞机的。D4.Youcanborrowmycar_____youpromisenottodrivetoofast.（2012江西）A.unlessB.evenifC.incaseD.aslongas解析：A项表示“除非，如果不”，B项表示“即使”，C项表示“万一，以防”，D项表示“如果，只要”。显然D项符合语意：你可以借用我的车子只要你承诺不要开车太快。D5.ourmanageobjectstoTom'sjoiningtheclub,weshallaccepthimasamember.（2010上海）A.UntilB.UnlessC.IfD.After解析：此句意思是“除非我们经理反对tom加入俱乐部，不然我们都应接受他成为其中一员。”B6.—Ourholidaycostalotofmoney.—Didit?Well,thatdoesn’tmatter______youenjoyedyourselves.（2010江西）A.aslongasB.unlessC.assoonasD.though解析：aslongas只要unless除非否则assoonas一就though虽然,后一句为只要你玩的开心,花多少钱就不重要。AChoosethebestanswerfromA,B,CandD.1.Atfirsthehatedthenewjobbutdecidedtogivehimselfafewmonthstosee______itgotanybetter.A.whenB.howC.whyD.ifD2.Youmayuseroomasyoulike____youcleanitupafterwardsA.sofarasB.solongasC.incaseD.evenifB3.---Shallwehaveourpicnictomorrow?---______itdoesn'train.A.UntilB.WhileC.OnceD.IfD4．—Ourholidaycostalotofmoney.—Didit?Well,thatdoesn’tmatter_____youenjoyedyourselves.A.aslongasB.unlessC.assoonasD.thoughA5.Thelittleboywon’tgotosleep_____