Section Ⅳ Discovering Useful Structures 语法项目———情态动词与过去将来时 Three years ago, when the College Entrance Examination would come① in three months, I was under great pressure. Once, because I stayed up late at night, I should fall asleep② in class.My parents would comfort me③ when I didn't do well in the exam.Gradually, I could adjust myself④ .When I went into the examination room, my mother cheered me on.She said, “May you succeed⑤ , boy！” [语法入门] ①would come表示过去将来时。 ②should fall asleep中should表示惊讶。 ③would comfort me中would表示习惯性动作。 ④could adjust myself 中could表示“能；会”。 ⑤May you succeed中may 表示祝愿。 一、情态动词的意义和用法 |自主感知| ①(教材典句)Oliver believes that with a million pound bank note a man could live a month in London. ②(教材典句)May we ask what you're doing in this country and what your plans are ③You must finish your homework this afternoon. ④(教材典句) Now if you'll excuse me, I ought to be on my way. ⑤I promise I will do my best to provide the best service for the Asian Games. ⑥You needn't come here this afternoon. ⑦How dare you say I'm unfair ⑧She can't have been to your house; she doesn't know your address. [我的发现] ①句中的could表示_____。 ②句中的may表示_____。 ③句中的must表示_____。 ④句中的ought to 表示_____。 ⑤句中的will表示_____。 ⑥句中的need表示_____。 ⑦句中的dare表示_____。 ⑧句中的can't have done表示_____。 |规则点拨| (一)情态动词的概念及特征 情态动词是一种本身有一定的意义，表示说话人对某一动作或状态的情绪、态度或语气的动词，但不能单独作谓语，只能和其他动词原形一起构成谓语。常见的情态动词有：can (could), may (might), must, need, ought to, dare, shall (should), will (would)等。 情态动词有以下特征： 1．在形式上，情态动词没有实义动词的各种变化，只有could, would, had to, might等几个过去式，其他情态动词如 must，ought to 等的过去式皆与一般式同形。 2．在意义上，大多数情态动词有多个意义，如 can可以表达“能力；可能；许可”等。 3．在用法上，情态动词与助动词一样，须后接动词原形，一起构成谓语。 (二)can与could的用法 1．can与could表示能力，意为“能；会”。 2．can与could表示请求和许可(could用来表示请求时，语气更委婉，回答时一般用 can)。 3．can与could用于肯定的陈述句中，表示理论上的可能性，意为“有时会；(有时)可能会”。 4．can与could表示可能性，用于表示把握比较大的推测，常用于疑问句和否定句中，can't/couldn't表示“不可能”。 Could you offer me a job here You can't open it until two o'clock. Rome can be pricey for travelers, which is why many choose to stay in a hostel (旅社)． I saw her go out just now.She can't be at home now. [对点练] (根据句意填入适当的情态动词或其否定式) ①That _____ be Mary, for she is in hospital. ②_____ you please do me a favor ③You _____ tell a lot about a man by how he treats his dogs. ④—Can this book be yours —No, it _____ be mine.It must be his. (三)may与might的用法 1．may与might在肯定句中表示允许，意为“可以”。 2．may与might在疑问句中用于征求许可(might表示的语气更委婉)。 3．may与might表示推测，意为“可能；或许”。 4．may ... ...
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