八年级英语上册_unit 2 keeping healthy topic 2 i must ask him to give up smoking section c情态动词can、may、must、need解析区别练习课件 （新版）仁爱版

UNIT2KeepingHealthyTOPIC2ImustaskhimtogiveupsmokingSectionC 情态动词can may must need解析区别练习 情态动词 情态动词后面 动词原形 情态动词没有人称和数的变化 1 can Icannotplaybasketball Ineedbuyacomputer 2 能 need 需要 Shecanrideahorse Amyneedbuyabook 3 否定式构成是在情态动词后面加 not Icanplaybasketball can 能 用法 表示能力 HecanspeakalittleEnglish Canyoufly 表示请求或允许 CanIhelpyou 表示猜测 ThatcannotbeourEnglishteacher becauseshehasgonetoShanghai could也可表示请求 语气委婉 主要用于疑问句 不可用于肯定句 答语应用can CouldIcometoseeyoutomorrow Yes youcan 否定答语可用No I mafraidnot 注意 用法 表示请求或允许 MayIgohome please 1 以may 表许可或请求 开头的一般疑问句 肯定回答用may 否定回答用mustn t或can t 2 在疑问句中不用于第二人称 表示可能性 用在肯定句 Youmayberight No you may 可以 Yes youmay 注意 might为may的过去式 但也可以代替may 语气较为婉转客气或更加不肯定 Youmightberight might mustn t youcan t 试比较 Youmaynotsmokehere 可能不 语气轻 Youcan tsmokehere 不能 重 Youmustn tsmokehere 决不可 最重 can t maynot mustn t 用法 既可以做情态动词 也可以做实意动词 实意动词 needtodosth 情态动词 needdosth Ineedbuyabighouse need 需要 Heneeddrivemehome DoIneedtobuyabighouse Heneedstobuyabighouse NeedIbuyabighouse Yes youmust No youneedn t don thaveto 不必要 Yes youdo No youdon t 用法 表示推测 肯定 一定 表示义务 必要或命令 Youmustcomeearlytomorrow MustIfinishmyhomeworkfirst Theymustbeathome Thelightison Yes youmust No youdon thaveto needn t must 必须 注意 must开头的疑问句 其否定回答通常用don thaveto或needn t 而不用mustn t mustn t 禁止 否定时表示 禁止 Youmustn tsmokehere 用法 It seleveno clock Ihavetogonow Itwasgettingdark Hehadtofinishtheworkfirst Idon thavetogonow Hedoesn thavetofinishtheworkfirst haveto 必须 注意 haveto表示客观因素Weareverygladattheparty butit s11 sowehavetoleavenow must表示主观因素Wemuststudyhardtofindagoodjobforourselves must 必须 haveto must区别 Mybrotherwasveryill soIcallthedoctorinthemiddleofthenight Hesaidthattheyworkhard Youdon thavetotellhimaboutit Youmustn ttellhimaboutit 你不一定要把此事告诉他 你一定不要把这件事告诉他 haveto must hadto must 区别 CanI Yes youcan No youcan t MayI Yes youmay No youcan t mustn t NeedI Yes youmust No youneedn t DoIneedto Yes youdo No youdon t MustI Yes youmust No youneedn t 找伙伴 Should应该Shouldn t不应该YoushouldfinishyourhomeworkontimeYoushouldn tgotobedtoolate Exercises 1 Mustwecleanthehousenow No you needn tB maynotC mustn tD can t2 Youreturnthebooknow Youcankeepitnextweekifyoulike A can tB mustn tC needn tD maynot3 Johnny youplaywiththeknife youhurtyourself A won t can tB mustn t mayC shouldn t mustD can t shouldn t4 Igobackbeforelunch No Idon tthinkyou A Need mustB Do needtoC Must havetoD May oughtto A C B C 5 Theteacher doalltheexercises butapupil A needn t mustB maynot mustC needn t needn tD can t must6 MustIfinishthisnovelthismorning No you A mustn tB mightnotC don thavetoD can t7 Thetaxi onlyholdsixpassengers Itisfull You takethenextone A may mayB can mayC may