Unit4 Grammar 语法讲义- must和have to以及特殊疑问词 to do-牛津译林版八年级英语下册

Unit4Grammar语法讲义---must和haveto以及特殊疑问词+todo一.must和haveto的区别I.must表示主语“必须”做某事，强调说话人的主观意愿;必须做某事（主观意愿）mustdosth.禁止做某事mustn’tdosth.例1：—MustIkeepthedooropen?—Yes,youmust.例2：—MustIbringmyhomeworkwhenIcomehere?—No,youneedn’t.—No,youdon’thaveto.II.haveto强调的是客观需要，意思是“不得不，得做某事”。不得不做某事（客观需要）havetodosth.不必做某事don’thavetodosth.haveto有人称和数的变化:hasto,hadto,willhaveto。注意：must表示必须，其否定形式为needn’t或don’thaveto，而不是mustn’t。mustn’t表示禁止。二.拓展：情态动词的用法情态动词用法常考的三种情况：表示可能性、猜测：can（一般表示对客观真理的猜测，不用于现实事件的猜测）----无否定could（can的过去式）易错点:may（表示对事件的猜测）----否定maynot（可能不）---过去式mightmust（一定）-----否定-can’t（不可能）例1：Therecanbealiensintheouterspace.------表示对科学真理的猜测例2：HecanbeLily’sfather.----错，can不用于现实事件的猜测改正：HemaybeLily’sfather.例2：ThereislightinMr.Li’soffice.He_________(一定)beinside.-----mustbe例3：Mr.LiisonbusinessinShanghai,sohe__________(不可能)beathome.---can’tbe例4：他可能不是李老师。HemaynotbeMr.Li.他可能是李老师。HemaybeMr.Li表示请求允许：may,might,can,could,mustn’t.例1:----Might/MayIsmokeinthisroom?----No,youmustn’t.例2：----May/MightItakethisbookoutoftheroom?----Yes,youcan.(No,youcan’t/mustn’t.)表示必须，必要：must一定；needn’t不必；don’thaveto不必。例：----Mustwehandinourexercisebookstoday?----Yes,youmust.----No,youdon’thaveto/youneedn’t. 练习1.Mike,you______playwithfire.You__________burnyourself.A.won’t;can’t B.mustn’t;may C.don’thaveto;must D.havegotto;shouldn’t2.---Where’smyumbrella?---It’sfinetoday.You____________takeanumbrellawithyou.A.can’t B.needn’t C.mustn’t D.shouldn’t3.I’msorry.I___________gonow.Myfathertoldmeonthephonethatmymotherwasill.A.must B.haveto C.may D.think4.—MustIfinishreadingthebookfirst?—No,you_______.Youmayfinishittomorrow.A.can’tB.mustn’tC.don’thavetoD.shouldn’t5.Allthestudents_________knowshoutingattheelderlyisimpolite.A.can B.couldC.must D.need6.--Where’smyumbrella?--It’sfinetoday.You______takeanumbrellawithyou.A.can’tB.needn’tC.mustn’tD.shouldn’t7.Mr.Collins________liketea.Hemakesacupofteaforhimselfeverymorning.A.must B.may C.can't D.mustn't8.—TheCCTVMarch15thEveningPartyshowedthatthesnack"spicystrip"whichchildrenlikeeatingispoisonous(有毒的).—Yes.Something______bedonetomakeproducerspayattentiontofoodsafety.A.need B.might C.may D.must9.Tomyjoy,we______gotothebank.Maryhaslentussomemoney.A.shouldn't B.needn’t C.couldn't D.wouldn't10.Healwaysmeanswhathesays.There______beareasonwhyhedidn'ttellthetruth.A.Must B.should C.may D.can11.--It'ssaidthatdrinkingcoffeecausescancer.DoIgiveitup?--Relax!NoteverythingonWeChatistrue.Infact,acoffeeadaykeepsthedoctoraway.A.mustB.mayC.canD.haveto三.特殊疑问词+todo用法：用于句中由来：来源于宾语从句，是宾语从句的简略形式当know,remember,decide,forget等动词后接宾语，并且从句主语与主句主语一致，从句可以简化成“疑问词+不定式”结构。Idon’tknowhowIshoulddothework.=Idon’tknowhowtodothework.IhavedecidedwhatIshoulddonext.=Ihavedecidedwhattodonext.宾语从句的主语和主句的间接宾语一致，也可简化。CouldyoutellmehowIcangetthere?=Couldyoutellmehowtogetthere?练习Theyknow___________tomeetat8:00tomorrow.(where,when)Canyoutellus_________totalkto?(who,where)Doyouknow_________tofixthecomputer?(who,how)Sandywantstoknowwhere_________(ask)foradvice.Myquestioniswhen__________(start).Bequiet!Wearetalkingaboutwhattime________(meet)atTaiheShoppingMall.It’stoodifficult.Idon’tknowhow__________(answer)it.Ireallydon’treallyknowwhen_________________(begin)themeeting.Ireallydon’t