第七讲 情态动词和虚拟语气-邦国教育2020高考英语总复习专练

第七讲 情态动词和虚拟语气 1、 知识整合 考点一 情态动词 1.can，be able to和could (1)can和be able to都表示能力，意思上没多大区别。但can只有现在和过去时，而be able to则有更多的形式。但当成功地完成某一具体动作时，通常不用could而用was/were able to来表示。这时was/were able to相当于managed to，表示经过一番努力，终于能够完成某事。 Her mother can speak French. The wounded man was still able to get to the village and was saved by the villagers in the end. (2)表示猜测“可能”，一般用于疑问句和否定句。 —Can the news be true? —It can't be true. Someone is knocking at the door.Who could it be? (3)can可以表示理论上的可能性，指常有的行为或情形，意为“有时会……”。 Anybody can make mistakes. (4)表示请求、允许(表请求时，口语中常用could代替can使语气更委婉，回答时用can)。 Can I go now? —Could I come to see you tomorrow? —Yes，you can.(否定答语可用No，I'm afraid not.) (5)表示惊异、怀疑、不相信的态度(主要用于否定句、疑问句或感叹句中)。 How can that be true？I can't believe my eyes and ears. How could you be so careless? (6)can的特殊用法。 can but只有；can't but不得不；can't...too再怎样也不为过/越……越好 I can but wait. I can't but wait. You can't be too patient to the customers. 2.may和might的用法 (1)表示允许、请求，might比may的语言更委婉一些。 —May I watch TV now? —Yes，you may.(Yes，please.) —No，you mustn't.(No，you'd better not.) (2)表示可能性时，might比may的可能性小，may表示的可能性比can小(主要用于陈述句、肯定或否定句，疑问句用can代替)。 The story may not be true. (3)表示祝愿(不用might) May you succeed! (4)may/might as well最好还是……，不妨 You might as well do it now. (5)may/might well很可能 He may well be late for class. 3.must，have to和ought to的用法 (1)must表示“必须，应该，一定要”。强调主观看法，只有现在时形式，否定式是must not(mustn't)。must开头的问句，其否定回答要用needn't或don't have to代替。 (2)must表示必然的结果。 All men must die. (3)must还可表示主语固执、偏要做他人不希望做的事。 It can't help；he must do that. (4)have to着重客观需要，能用于更多时态(过去时或将来时)。 He will have to be there before ten. (5)ought to表示义务和责任，“应该”，比should语气要强。 You ought to take care of yourself. 4.need和dare的用法 (1)need表示“需要，必要”，只能用于否定句和疑问句。在肯定句中，常用must和have to代替。 (2)dare表示“敢”，通常用于否定句、疑问句和条件状语从句中。 Dare you go home alone at eleven in the evening? (3)need和dare的特殊用法 ①need表“需要”时，可用want，require代替。 The desk needs to be repaired./The desk needs repairing. ②dare作实义动词时，在肯定句中要接to，在疑问句和否定句中to可省去。 He dares to catch a snake. I do not dare(to)com