情态动词没有人称和数的变化，有词义，但是不完整，不能单独做谓语，必须(bìxū)和不带to的动词不定式连用。(1)Hecanrunthe100msprintin11seconds.(2)Canthislittlegirlreadbeforeshegoestotheprimaryschool?can/beabletoobligationhaveto/must2)must表示(biǎoshì)主观看法，haveto则侧重于客观需要。如：Wemustbestrictwithourselvesineverything．Incitieswithmanycars,somepeoplehavetowearmasks．ShemightwinamedalattheOlympics.Shemaybeathomenow.Shecouldreadandwriteattheageof4.Sheshouldcometojoinus.Sheoughtto/will/musthelpmewheneverIamintrouble.can/could/may/might--Will/Can/Could/Wouldyouhelpmewithmytraining?--Yes,Iwill/can/can/will.makesuggestionsmakeoffers和其他时态(shítài)的连用musthavedone的反意(fǎnyì)疑问句shall可以用来征求对方意见。用于第一、三人称。此外它也可以用来表示说话人的命令、警告、允诺(yǔnnuò)、威胁或决心等，这时它用于第二、三人称。如：Shallshegototheconcertwithusthisevening？(征求意见)Youshallgotothefrontatonce．(命令)Don’tworry．Youshallgettheanswerthisveryafternoon．（允诺(yǔnnuò)）Heshallbesorryoneday．Itellyou．(警告)Nothingshallstopusfromfightingagainstpollution．(决心)will在肯定句中表示(biǎoshì)意愿或决心时，是可以用于条件状语从句的。在疑问句中用于第二、三人称表示(biǎoshì)意愿。如：Willyougohikingwithmeinthemountain?Willhepayforme?Ifyouwilllistentome,I’llgiveyousomeadviceonhowtolearnEnglish．Ifyouwillcomethisway,themanagerwillmeetyou．mustn’t/needn’tneed/dare用作实义动词(dòngcí)时，可用于各种句式．Weneedtotellhimthenews.Youdon’tneedtotellhimthenews.Dotheflowersneedwatering?Ididn’tdaretotellyouthetruth.Wouldyoudaretocatchthesnakewithyourhand?Theboydarestodoanythinghelikes.Haveatry!1.Aleft-luggageofficeisaplacewherebags____beleftforashorttime,especiallyatarailwaystation.A.shouldB.canC.mustD.will3.--Theroomissodirty.____wecleanit?--Ofcourse.A.WillB.ShallC.WouldD.Do5.--Ihearyou’vegotasetofvaluableAustraliancoins.___Ihavealook?--Yes,certainly.A.DoB.MayC.ShallD.Should7.--AreyoucomingtoJeff’sparty?--I’mnotsure.I__gototheconcertinstead.A.mustB.wouldC.shouldD.might9.--WhencanIcomeforthephotos?Ineedthemtomorrowafternoon.--They___bereadybyby12:00.A.canB.shouldC.mightD.need11.Whenhewasthere,he___gotothatcoffeeshopatthecornerafterworkeveryday.A.wouldB.shouldC.hadbetterD.m