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语法：情态动词must、haveto和havegotto情态动词must和haveto都有“必须”的含义，它们的用法如下：（一）、must“必须”、“应该”的用法:1.must表示“必须”、“应该”。例如：①Wemustprotectourenvironment.(我们必须保护环境。）②Everyonemustobeytherule.（人人必须遵守制度。）2.must的否定形式mustnot表示“不应该”、“禁止”、“不准”。语气比较强烈。例如：①Youmustn’tspeaklikethat.(你不应该像那样讲话。）②Youmustn’tbelateforschool.（你不应该上学迟到。）3.在回答must的问句时，肯定形式用must来回答，但否定形式用needn’t或don’thaveto来回答。而不用mustn’t来回答。例如：①——MustIbehomebefore8o’clock?(8点之前我必须回家吗？)——Yes,youmust.No,youneedn’t./No,youdon’thaveto.（是，你必须。）（不，你不必。）4.must还可表示推测，意思是“一定”、“必定”，一般只用于肯定句中。分三种情况：1.）对于现在状态的推测，我们用：must+v.（状态动词或系动词），例如：①Hemustbeathome.(他准在家里。）②Theremustbesomechildrenintheroom.（房间里准有些孩子。）2.）对于现在动作的推测，我们用：must+be+doing（行为动词），例如：①Theymustbecleaningtheirroom.(他们准是在打扫房间。）②HemustbewatchingTV.（他准是在看电视。）3.）对于过去事实的推测，我们用：must+have+过去分词，例如:①Itmusthaverainedlastnight.(昨晚准是下雨了。）②Ididn’thearthephone.Imusthavebeenasleep.（我没有听到电话，我准是睡着了。）（二）、haveto表示“必须”、“不得不”，例如：①Hehastostayinbedfor3or4days.(他必须卧床休息三四天。）②Wewillhavetogetupearlytomorrow.（明天我们必须早起。）（三）、havegotto是haveto的口语形式。例如：①I’vegottoleaveforNanjing.(我不得不去南京。)*Must与haveto的区别：must表示的是说话人的主观看法，而haveto则表示的是客观需要。Must一般只有现在时，而haveto有更多的形式。①Imustgonow.(主观看法)②Mymotherisill,soIhavetogonow.(客观需要)*Haveto与havegotto的区别：havegotto虽然是haveto的口语形式，但二者在用法上有严格的区别：haveto的前面还可以用情态动词或助动词，而havegotto却不可以；haveto的否定形式为don’t/doesn’t/didn’t+haveto,疑问式为Do/Does/Did+主语+haveto…?而havegotto的否定形式是在have后加not,疑问式把have提前。例如：①Wedon’thavetogohome.①Doyouhavetogohome?②Wehaven’tgottogohome.②Haveyougottogohome?一、.Fillintheblanksusinghaveto,havegotto,must,should,oughtto,hadbetter.1.You_____________notgetdownuntilthebushasstopped.2.They_____________beencouragedtospeakEnglishafterclass.3.Youoften_____________waitalongtimeforabus.4.We_____________goandseeMarytomorrow,butIdon’tthinkwewill.5.I_____________notmissmytrain.6.Whentraveling,you_____________takecareofyourhealth.7.Insomepartsoftheworld,you_____________boilthewaterbeforedrinkingit.8.Ifyouhaveastomachpain,you_____________drinkhotweaktea.9.You_____________notswimimmediatelyafteraheavemeal.10.You_____________notwakemeupwhenyoucomein.11.He_____________beill,forhelookssopale.12.You_____________nothavegivenhimthemoney.13.It’sgettinglate.IamafraidI_____________go.二、Choosethebestanswer.1.----MustIdoitnow?-----No,you_______.A.needn’tB.don’thavetoC.mustn’tD.AorB2.It’snearlyseveno’clock.Jack______behereatanytime.A.mustB.needCshouldDcan.3.------WhencanIcomeforthesephotos?Ineedthemtomorrowafternoon.-------They____bereadyby12:00.A.canB.shouldC.mightD.need4.Sorry,I’mlate.I________haveturnedoffthealarmo’clockandgonebacktosleepagain.A.mightB.shouldC.canD.will5.ItoldSallyhowtogetthere,butperhapsI________forher.A.hadtowriteitoutB.musthavewrittenitoutC.shouldhavewrittenitoutD.oughttowriteitout6.Jenny________havekeptherword.Iwonderwhyshechangedhermind.A.mustB.shouldC.needD.would7.Tomoughtnotto________meyoursecret,buthemeantnoharm.A.havetoldB.tellC.betellingD.havingtold8.Sir,you________besittinginthewaitingroom.Itisforwomenandchildrenonly.A.oughtn’ttoB.can’tbeC.won’tD.needn’t9.Ifyoureallywantyourselftobeingoodhealth,youmust______always______somuch.A.not,besmokingB.not,havesmokedC.not,tosmokeD.benot,smoking10.Ididn’thearthephone,I________asleep.A.mustbeB.musthavebeenC.shouldbeD.shouldhavebeen11.Iwasreallyanxiousaboutyou.You________homewithoutaword.A.mustn’tleaveB.shouldn’thaveleftC.couldn’thaveleftD.needn’tleave12.You’dbettergoatonce,_________you?A.shouldn’tB.wouldn’tC.hadn’tD.couldn’t13.Sheoughttobepraised,_________?A.oughtsheB.sheoughtC.oughtn’tsheD.sheoughtn’t14.He_________gotherebytrain.A.oughtn’ttoB.oughtn’tC.oughttonotD.didn’toughtto15.--------Look,it_________beMr.Wang.------------No,it_________behim.Hehasgoneabroad.A.may;mustn’tB.must;maynotC.must;can’tD.can;maynot三、Correctthemistakeineachsentence:1.Youhavebetterhurryup.2.Thetaxishouldarriveat8:30,butitdidn’tturnup.3.Thatmustn’tbethepostman---------it’sonlyseveno’clock.4.Peopleoughtvoteeveniftheydon’tagreewithanyofthecandidates.