高考英语专题之情态动词状元必读情态动词的考查要点：1. 情态动词can, could, may, might, must, shall, should和ought to 的用法。2. must和have to 的区别。3. can和may 在短语中的应用。4. 情态动词在高考试卷中一般占2-3分，但在书面表达中也会考查考生正确运用情态动词来表达意思的能力。专家点拨一、知识精讲 情态动词表示说话者对某一动作或状态的态度，可表示“可能”、“可以”、“需要”、“必须”或“应当”等意。情态动词没有人称和数的变化。但不能单独作谓语动词用，必须和不带to的不定式连用构成谓语动词。但情态动词ought和have要和带to的动词不定式连用，在句中作谓语。 将情态动词置于主语之前即可构成其疑问式，在情态动词之后加not即可构成其否定式。1. can和could (could为can的过去式) 的基本用法（1）表示能力。【例句】He can speak English better than you.When he was only five, he could swim well.（2）在疑问句和否定句中表示“怀疑”、“猜测”或“可能性”。【例句】Can this green bike be Liu Dongs? The glasses cant be Marys; she never wears glasses.（3）表示“许可”时，can可以和may换用。【例句】You can (may) go home now. You can not leave here till I come back. （4）如果要表示婉转语气，可用could代替can，这时could不再是can的过去, 但答语要用can。【例句】Could you come again tomorrow? Could you help me with the heavy bag?Yes, I can.（5）can和be able to都可表示能力，两者在意思上没有什么区别。【例句】He will be able to do the work better. (can只有现在式和过去式，而be able to中的be可用各种时态)The fire spread quickly but everyone was able to escape from it. (表示成功地完成某一具体动作时，通常不用could) 状元典例1Just be patient. You _ expect the world to change so soon.A. cant B. neednt C. may not D. mustnt答案：A思路分析：句意为：耐心点儿。你不能期盼这个世界变化这么快。cant在否定句中表推测时译为“不可能”，表能力时译为“不能够”，也可以表示命令，此时译为“不允许”，但其语气比mustnt弱, 具有劝慰的意思, 根据句意此题选A, cant表示劝慰。状元典例2Im afraid Mr. Harding _ see you now. Hes busy.A. cant B. mustnt C. shouldnt D. neednt答案：A思路分析：结合语境, 根据情态动词用于疑问或否定句中表推测时要用cant，可知选A。2. may和might (might为may的过去式)的基本用法 （1）表示允许或征询对方许可，译为“可以”。【例句】You may use my dictionary. She told me that I might leave if I wanted.注意1：在回答对方说“可以做某事”或“不可以做某事”时，一般不用may或may not，以避免语气生硬。【例句】May I play the computer game now, Mom? Yes, please. 或Certainly.（一般不用may）No, you mustnt. (表示“阻止”或“禁止”对方做某事)注意2：在征求对方许可时，用Might I? 比用May I? 语气更婉转，此时might不是may的过去式。【例句】Might I have a look at your new iPhone? （2）may或 might都可以表示可能性，表示“或许”、“可能”时, might的语气更加不肯定。【例句】They may be in the library now .（可能性较大）来源:学*科*网Z*X*X*KThey might be in the library now.（可能性较小）（3）may放在句首用来表示祝愿。【例句】May you have a good journey.来源:学科网ZXXK状元典例1 I take the book out? Im afraid not.A. Will B. May C. Must D. Need答案：B思路分析：表请求时可用情态动词can, may, could, might，表允许时用can, may。句意为：“我可以将这本书带出去吗？” “恐怕不行”。故应选表请求的情态动词may。状元典例2Helen go on the trip with us, but she isnt quite sure yet.A. shall B. must C. may D. can答案：C思路分析：may表示一种可能性。如果没有具体的语境，B、D两项也可入选，但意思就不同了。3. must的基本用法(1) must表示“必须”、“应该”之意，mustnt表示“不应该”、“不准”、“不允许”或“禁止”之意。【例句】We must study hard and make progress every day. Everyone must obey the traffic rules.Students mustnt enter the lab without the teachers permission. (2) 以must提出的疑问句，如作否定回答时，要用neednt或用dont (doesnt) have to (不必)来回答，而不用mustnt。【例句】 Must we finish the work tomorrow? No, you neednt (dont have to), but you must finish it in three days. (3) 在肯定句中must可以表示推测，表示“一定”或“必定”。【例句】 Whose new bike can it be? It must be Liu Dongs. I know his father has just bought him a new one.(4) 表示“偏要、硬要做某事”。【例句】Its nearly 11 oclock. Must you make so much noise?(5) 与must有关的反意疑问句。【例句】He must be from the south, isnt he?It must have rained last night, for the road is very muddy, didnt it?He must have gone to Beijing, hasnt he?状元典例1I have told you the truth. _ I keep repeating it?A. Must B. Can C. May D. Will答案：A思路分析：must 必须, 一定；can 可以, 能够；may 也许；will 意愿（倾向性动作）。前半句说“我告诉你事实了”，这里用的是现在完成时，表示过去的动作对现在造成了影响， 既然我已经说了，我还必须不断重复吗？状元典例2 May I take this book out of the reading room? No, you . You read it in here. A. mightnt B. wont C. neednt D. mustnt答案：D思路分析：英语中用could, might表示询问或征求意见的问句中, 肯定性回答要用can或may来代替could或might，而用may或might表示征求意见的问句中，否定回答时要用mustnt, 故本题选D。状元典例3If you_ smoke, please go outside.A. can B. should C. must D. may 答案：C思路分析：句意为：如果你非要吸烟，就请到外面去。此句考查must作 “非要，硬要”之意时的用法。4. shall的基本用法(1) shall用作情态动词时，用于第二、三人称作主语的陈述句中，表示说话者的“命令”、“警告”、“强制”、“威胁”或“允诺”等意。【例句】He shall go first, whether he wants to or not. （命令）You shall get a new computer if you win the first place in the game. （承诺）You shall fail if you dont work harder（警告）He shall be punished. （威胁）Each competitor shall wear a number. (规定) (2) 在疑问句中，shall用于第一、三人称，表示说话者征求对方意见或请求指示。【例句】Shall I open the door?Mike is outside. Shall he come in?状元典例1No student go out of school after ten oclock at night without the teachers permission. A. willB. must C. mayD. shall答案：D思路分析：句意为：未经老师允许，所有的学生在晚上10点钟后都不得出校门。这是学校的规定，所以要选D，shall用在第二、三人称作主语的陈述句中表示“按规定做”。状元典例2 I havent got the reference book yet, but Ill have a test on the subject next month. Dont worry. You _ have it by Friday.A. could B. shall C. must D. may w_答案：B思路分析：shall用在第二人称作主语的陈述句