情态动词;第四章;;情态动词（一）

情态动词;第四章;;情态动词

（一）情态动词表示说话人对动作或状态的各种观点和看在句中不能单独但不完全,是所谓的〃帮助性〃动词,法，如须要、推想、意愿或疑心等情态动词有词义,充当谓语情态动词的各种形式见下表:a.

一、情态动词的特征和形式情态动词may mightcan couldmust have to ought to willwouldshall shouldneeddare used to否认式may notmight notcannotcan notcould notmust notdonot haveto oughtnot towill notwould notshall notshouldnot neednot darenot usednot todid notuse to简洁否认式（老式英语，此时此刻不常见）mayntmightntcantcouldntmustntdont haveto（否认句中可省略）oughtnt totowontwouldnt（只用于英国英语）shantshouldntneedntdarentusednt to情态动词除等外,后面只didnt useto b.ought to,usedto接不带的不定式to.情态动词1+do你不该这样马虎大意you shouldntbe socareless.jessica toldhim yesterdayshe mightnot goon thetrip.杰西卡昨天告知他，她可能不去旅行了difficulties canand must be overcome.困难能够而且必需克制.情态动词2+be doingshe mustbelistening topop music.她确定在听流行音乐you shouldbe reviewingyour lessons.你应当在复习功课my mothermaymight becooking now.我妈妈可能正在做饭.情态动词3+have donethey mighthave visitedthe greatwall.他们可能参观过长城了hemust have gotup veryearly tocatch thetrain.他必需起得很早去赶火车了you oughtto havecome earlier.你本该早一点儿来.情态动词4+be donethisword canalso beused asa verb.这个词也可以用作动词something mustbe doneto stoppollution.必需接受措施来制止污染the workoughttohave beenfinished longago.这工作早就该完成了情态动词第三人称单数一般此时此刻时没有词形变更c.you oughtto weara raincoat.你应当穿件雨衣she oughtto weara raincoat.她应当穿件雨衣plants musthave oxygen in order to live.为了存活植物必需有氧气a plantmusthaveoxygeninordertolive.为了存活植物必需有氧气情态动词的时态并不是区分时间的主要标记在一d.些场合中，情态动词的此时此刻式和过去式都可以表示此时此刻时间、过去时间或将来时间im afraidit mightrain tonight.我看今晚可能要下雨could iborrow yourthermos我可以借用你的暖水瓶吗？its anice daytoday,we couldgo fora walk.情态动词是相互排斥的，一般不允许两个意义相近e.今日天气不错，我们可以出去散闲逛的情态动词连用【误】soldiers musthaveto obey orders.【正】soldiers havetoobey orders.军人必需听从叮嘱【正】soldiers mustobeyorders.军人必需听从叮嘱【误】can ibe ableto borrow two books at a time【正】can iborrowtwo booksat atime我能一次借两本书吗？【正】will ibe ableto borrowtwobooksatatime我能一次借两本书吗？。