情态动词一can-may-must的用法

情态动词can,may,must的用法•情态动词后接动词原形;•没有人称和数的变化;•不能单独作谓语,与后面的动词共同作谓语;•其否定形式在后面直接加not。Modalverbs情态动词•can/cannot•may/maynot•must/mustnotModalverbs情态动词can/cannot1.表示能力(会)MarycanspeakEnglish,butshecannotspeakFrench.2.表示允许(可以)也可用could(不是过去式)更委婉Can/CouldIuseyourdictionary?3.表示推测(可能)----通常用于否定形式Hecan’tbeintheoffice.Isawhimgooutjustnow.1.S1___Kitty____?S2_____________.2.S1____Kitty____?S2_____________.CanspellYes,shecanCanaddNo,shecan’tmay/maynot1.表示允许(可以)也可用might更委婉May/MightIcomein?2.表示推测(可能)----通常用于肯定形式Shemaybestillwaitingforus.3.表示祝愿Mayyouhaveahappyweekend.may的用法:may/maynot●以may开头的疑问句，其否定回答用can’t或mustn’t。--MayIgohomenow?--Yes,youmay.No,youcan’t/mustn’t.maynot的用法:Answers:1.MayIcarryyourbagforyou?2.MayIopenthedoor?3.MayIgetyouachair?4.MayIswitchontheTV?5.MayIborrowyournewbicycle?must/mustnot1.must表示必须Youmustdoyourhomeworkfirst.2.must表示“一定”(肯定性推测)语气较强Hemustbeathome.must的用法:must/mustnot1.mustn’t表示禁止(不准；不允许)Youmustn’tsmokehere.2.以must开头的疑问句，其否定回答要用needn’t.--MustIcleantheclassroomnow?--Yes,youmust.No,youneedn’t.mustnot的用法:五.haveto的用法•表示客观需要“不得不，必须”Imissedthetrain,soIhadtotakeataxi.在疑问句和否定句中，haveto需借助助动词do，Didhehavetodoit?Youdon‘thavetogothere.（不必，不需要）‖needn’t六need的用法•后加动词原形表示需要，必须，用于否定和疑问句否定：needn’t（不需要），疑问将need提前注：用于肯定句时，常作实意动词用：needtodosthNeedwereturnthemagazinestoday？yes，youmust./no,youneedn’t.Youneednotdothis。疑问句回答：同mustWhatdothesignsmean?Doyouknow?Youmustnotcycle.Youmustbecareful.Youmustturnleft.Youmustnotenter.Youmustpaytenyuan.Youmustkeepsilent.Youmustnotturnright.Youmustnotsmoke.Ⅰ.用适当的情态动词填空：。1.Icanplayfootball.__________youswim?2.Don’tworry.You________returnmethisbooktomorrow.3.Mygrandmaisill.You_______talksoloudlyhere.4.Ican’tplaywithyou.I__________finishmyhomeworkfirst.5.I__________getupearlytomorrow.becauseIhaveameeting.6.______________youpleaseopenthewindow?Canmaycan’tmustmustCan9.Nobody___________livewithoutair.10._________hespeakChinese?Yes,alittle.11.Thebook_________bereturnedbeforeSaturday.12.__________Icomein?Yes,please.13.You________giveupsmokingatonce.It’sbadforyourhealth.14.Excuseme._________Iaskyouaquestion?15.__________youtellmewherethestationis?16._______Ifinishtheworknow?No,you_________.You_______doitthisevening.17.MayIuseyourdictionary?Sorry,you_________.Iamusingitnow.18.Lookattheground.It’sverywet.It_______haverainedlastnight.canCanmustMaymustMayCanMustneedn’tcancan’tmust