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初中英语――if引导的条件状语从句在if引导的条件状语从句中，if和条件句位置灵活，可直接放在主句后面，若if条件句放句首，从句后面要加逗号，和主句隔开。还要注意前后时态一致原则.引导条件状语从句的连接词主要有：if(如果）、unless（除非）或aslongas（只要）等。unless在意思上等于if...not。一、条件状语从句用法1、引导条件状语从句最常用的连词是if,由if引导的条件状语从句表示在某种条件下某事很可能发生。如：Ifyouaskhim,hewillhelpyou.如果你请他帮忙,他会帮你的。Ifyoufailintheexam,youwilllethimdown.如果你考试不及格,你会让他失望的。另外,if从句还表示不可实现的条件或根本不可能存在的条件,也就是一种虚拟的条件或假设,从句多用一般过去时或过去完成时。如:IfIwereyou,Iwouldinvitehimtotheparty.如果我是你,我会邀请他参加聚会。2、unless=if...not.除非,若不,除非在……的时候例如：Let'sgooutforawalkunlessyouaretootired.=Ifyouarenottootired,let'sgooutforawalk.Unlessitrains,thegamewillbeplayed.除非下雨,比赛将照常进行。二、时态问题在条件状语从句中，要注意“主将从现”的规定，即主句用一般将来时，从句用一般现在时表示将来时。例句：IwillcometoseeyouifIhavetime.我有时间，我就来看你。三如果if条件句谈论的是重复发生和预示要发生的情景和事件，则主从句大多用一般现在时态。如：Ifbearsareindanger,theyattackpeople.误区提醒if既可以引导条件状语从句，表示“如果”，也可以引导宾语从句，表达“是否”。辨别它在这两种从句中的时态是我们经常容易出错的地方。另外，if和unless的用法也需注意。典型例题：----Iwonderifyourwifetotheparty.----Ifyourwife_________,sowillmine。.A.willgo，goB.willgo,goesC.goes,willgoD.willgo,willgo解析：第一句中if表示“是否”，引导宾语从句，用将来时willgo；第二句“如果你的妻子去，我的妻子也去”，if引导条件状语从句，用一般现在时表示将来时。yourwife，单三人称主语，所以用goes。总结IF引导的一、表示将来可能发生的：(1)Ifsbdoessth,sbwilldosth=sbwilldosthifsbdoessth主句一般将来时从句一般现在时(2)主句为祈使句或情态动词形式Ifsbdoessth,pleasedosthIfsbdoessth,sbmay(情态动词)dosth二、表必然发生的Ifsbdoessth,sb/sthdoessth=sb/sthdosthifsbdoessth主句一般现在时，从句一般现在时（相当于when引导的从句）Unless引导的sbwilldosthunlesssbdoessthifsbdoesnotdosth练习1.He______(fail)intheexamifhe______(notstudy)hard.2.Unlessyou______(leave)now,you______(be)late.3.We______(have)abarbecueunlessit______(rain).4.Hurryup,oryouwillmissthebus.（同义句转换）___youdon’thurryup,you____catchtheearlybus.5.Studyhard,oryou’llmissfallbehind.（同义句转换）______youstudyhard,you______fallbehind.6.Ifyoudon’tputonyourscarf,you’llcatchcold.（同义句转换）Putonyourscarf,_____you’llcatchcold.7.Idon’tknowifit_______tomorrow.）(表是否，用将来时态)Ifit____,Iwon’tgoshopping.(rain)（表如果，用现在时态）8.Iwanttoknowifhe_________(come)tomorrow,ifhe_______(come),I__________(give)themassagetohim.9.Pleaseletusknowifhe________(arrive)tomorrow.请告诉我们他明天是否会来Pleaseletusknowifhe_________(arrive)tomorrow.如果他明天来的话请告诉我们10.I’msureifhe_____(go)totheparty,he________(have)agreattime.11.Iftherain_______(stop)tonight,wewillgotothecinema.12.I’llbuyacomputerifI______(have)enoughmoney.13.You_________(notget)nervousifyou_____(do)enoughexercise.14.Ifshe____(be)kindtome,I__________(notargue)withher.15.Ifyou_____(pay)moreattentiontothat,he_________(notget)injured.16.MrLiwillbemadifwe_______(break)therules.17.Ifit_____(be)cloudy,they_______(notgo)therebyair.18.ShallIsay“Hello”whentheforeigner______(come)intotheclassroom?19.He’llgetbettergradesifhe_________(study)hard.20.Ifyouworkreallyhard,you_______(be)famousandrich.if条件状语从句的时态练习一．在正确的答案下划一条线。1.Daina(willgo/go/goes)toEuropeifshe(willpass/pass/passes)theexams.2.Thegraduates(willteach/teach/teaches)inthepoorvillageiftheMinistryofEducation(willagree/agree/agrees)soon.3.IfaUFO(willland/land/lands)infrontofme,I(willgo/go/goes)intolookforthealien.4.Ifhe(willhave/have/has)money,he(willbulid/build/builds)asciencelab.5.Don’twaitformeifI(am/willbe)late.6.They(won’t/don’t)gotothebeachifit(willrain/rain/rains).7.I(willcall/call)youifhe(willstay/stay/stays)athome.8.(Will/Do/Does)hevisitthemuseumifhe(won’t/don’t/doesn’t)gettired?9.Where(will/do/does)theyliveifthey(willmiss/miss/misses)thebus?二、用所给词的适当形式填空1.Ifyou________(feel)tired,you_______________(have)tohavearest.3.Ifthere__________(be)fewertrees,there_______________(be)morepollution.5.IfMarcia_____________(live)alone,she___________________(keep)apetparrot.6.Lana________________(buy)anewdressiftheoldone____________(be)outofstyle.7.Thetwins______________(fight)ifthey_______________(argue).8.I____________(have)abakesaleifI_____________(need)moneyforeducation.9.Peter_____________(send)meabeautifulsouvenirifhe________________(tour)Spain.10.IfMrGreen___________(say)Iamhard-working,myparents_________(feel)glad.11.I____________(go)tothebeachifit________________(notrain)thisweek.12.__________they__________(have)amatchiftheP.E.teacher_____________(be)busy?13.He____(write)alettertohisgrandparentsifhe____(get)hisreportcardthisweek.14.Ifshe____________(get)uplate,she_____________(notcatch)theearlybus.15.Peter________(major)inEnglishifhe____(pass)theexamsinPekingUniversity.Ⅰ.单项选择（15分）1.Ifyou_____totheparty,you’llhaveagreattime.A.willgoB.wentC.goD.going2.Itwillbealongtime____Peter_____hiswork.A.since,hasfinishedB.after,finishesC.when,willfinishD.before,finishes.3.Whatwillfather_____usfromJapan?A.takeB.bringC.carryD.make4.Weifangisfamous______kites.A.forB.toC.onD.with5．I____hertheanswerifshe____me.A.cantell,willaskB.willtell,willaskC.wouldtell,askD.willtell,asks6.–Whatareyougoingtodotomorrow?--We’llgotothelibrarytomorrowifit___.A.isn’trainB.rainC.won’trainD.doesn’train7.—Doyouknowwhenhewillcomebacktomorrow?--Sorry,Idon’tknow.Whenhe____back,I’lltellyou.A.comesB.willcomeC.comeD.maycome8.Whatwillyoudoifyou_____totheoldfolk’shomevisit?A.goB.wentC.goingD.willgo9.IfIeat____food,I’llbeveryfat.A.toomanyB.manytooC.toomuchD.muchtoo10.I’llgivethebooktohimifhe___