江苏省高三英语考前赢分30天第23天.doc

江苏省2013年高三英语考前赢分30天第23天情态动词的用法一、几组情态动词的基本用法1can, be able to (1) 表示能力，can只有一般式和过去式，而be able to有更多的时态。当be able to用于一般现在时中可以与can互换，但在一般过去时中不可互换，因为was / were able to表示过去既有能力而且设法干了，而could往往表示有能力而并未使用它。如：he can drive a car. /he is able to drive a car.he could swim, but he didnt jump into the river to save the child.(2) can表示请求和允许，此时可与may互换，在疑问句中还可用could, might代替。could和might不是过去式，只是语气更委婉，不能用于肯定句和答语中。2may, might（1）表示请求和允许。might比 may语气更委婉，而不是过去式。否定回答时可用cant或mustnt，表示“不可以，禁止”。2）用于祈使句，表示祝愿。may you succeed!4dare, need (1) dare作情态动词用时, 常用于疑问句、否定句和条件从句中, 过去式形式为dared。need 作情态动词用时, 常用于疑问句、否定句。如：how dare you say im unfair?need i finish the work today? yes, you must. / no, you neednt. (2) dare和 need作实义动词用时，有人称、时态和数的变化。he doesnt dare to go there.my hair needs cutting/to be cut.5shall, should ,ought to (1) shall 用于第一人称，征求对方的意见。what shall we do this evening?(2) shall 用于第二、三人称，表示说话人给对方的命令、警告、允诺或威胁。you shall fail if you dont work hard. (警告) he shall have the book when i finish it. (允诺)(3) should, ought to表示“应该”。ought to表示义务或责任，比should语气重。表示劝告、建议和命令时，should, ought to可通用，但在疑问句中常用should。 you should / ought to go to class right away.should i open the window?二、情态动词表示推测 在情态动词的推测性用法中，must, can, may, might, could 各用于不同的句型：must 只用于肯定句中；can/could 用于否定句和疑问句，不能用于肯定句；may/might用于肯定句和否定句，不能用于疑问句中。另外还应注意 cant 表示“不可能”，may not 表示“可能不”。如果有把握说明自己的猜测，一般应该用 must和cant，而不是 may, may not。 he cant have stolen the money; he is not such kind of person. some pleasant thing must have happened to him. he is so excited. 注意以下句子中推测性谓语动词发生的时间。 there must have been no one in, for nobody answered the phone. （推测过去的事情）they must be talking about something very secret. （推测正在进行的事情）he must be badly ill. he looks so pale. （推测现在的状态）there may be a terrible storm in the following few days. （推测将来发生的事情）三、“ 情态动词 + 动词的完成形式 ”的含义及用法 经典例题2.she looks very happy. she _ have passed the exam.（2007 江苏卷 22） i guess so. its not difficult after all. a. shouldb. couldc. mustd. might 考前赢分第23天 爱练才会赢前日回顾1. a number of people _ for the delegation，but the number of economists _ to three. a. were selected; were limitedb. selected; limitedc. were selected; limited d. were selected; was limited4. light and heat _ often sent out together with heavy smoke. a. isb. wasc. ared. being5. growing around the lake _ wild flowers of different colors. a. isb. arec. hasd. have当天巩固1. john, look at the time. _you play the piano at such a late time?a. canb. mustc. mayd. would2.will you stay for lunch? sorry, _. my brother is coming to see me. a. i mustntb. i cantc. i needntd. i wont3. the fire spread through the hotel very quickly but everyone _ get out. a. had tob. would c. was able tod. could4. i was really anxious about you. you _ home without a word. a. mustnt leaveb. shouldnt have leftc. couldnt have left d. neednt leave5. i thought you _ like something to read，so i have brought you some books. a. mayb. mightc. couldd. must6.sara has just come back from new york and she looks very happy. she _ her trip very much. a. might enjoyb. should have enjoyedc. might have enjoyedd. must enjoy7.excuse me, but i want to use your computer to type a report. you _ have my computer if you dont take care of it.