英语专业四级考试必考语法9-情态动词

• He used to be much better off than he is now.
• He would be much …… (wrong)
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• Would侧重叙述过去, 而used to 强调过去和现在的对比。
• Sometimes she would give me some pleasant surprises.
• She has not been able to work out the complex problem.
ought to的否定式
• ought to的否定式是ought not to，疑问句只把ought提前。
• You ought to be responsible for yourself.
• Do we have to wait for him to start dinner?
• Does he have to show you the tickets to enter the cinema? • Did I have to do the other task as well?
• You don’t have to come in person.
• You might as well wait to see what I can do for you.
• You might as well leave now.
• We might as well try a second time to see what’s wrong with the equipment.
• My mother used to be hot-tempered, but now she is very mild.
情态动词的完成式
needn‘t have done 表示过去本不必做的事情
• You needn’t have done all the calculation by yourself. We have computers to do that sort of work. • She needn’t have risen so early. There was no hurry. • They needn’t have brought so much food with them. We had enough for all the guests.
来。
• We had to resort to force in that case. • We will have to reconsider the whole thing if this plan fails.
• One must have faith in life.
have to
• have to的疑问句和否定句都要用助动词do/does，过去式则用did。
can‘t/couldn’t have done 对过去事情的否定猜测
• (must have done的否定形式） • It can’t have been her. She has gone to Shanghai. • You can’t have seen me in the meeting last week. I was on a business trip then. • He can’t have worked hard. I have seen him playing with his neighbors very often.
• Must he arrive very early?
• No, he doesn’t have to / No, he needn’t.
Must & have to
• Must: 主观上认为“必须” 作某事。 • Have to: 受客观情况迫使而“不得不” 作某事
• You must work harder now if you want to find a satisfactory job after graduation. • Children in remote areas have to quit school simply because their parents cannot afford their
• May be （可能是）--- maybe （或许）（副词）
• The news may be true.
• Maybe the news is true.
• She may be waiting for you at home. • Maybe she is waiting for you at home.
பைடு நூலகம்• 否定回答：needn’t或don’t /doesn’t have to
• Must I come as early as 6 tomorrow morning?
• Yes, you must.
• No, you needn’t. / No, you don’t have to.
Mustn’t & Needn’t
• She doesn’t have to bring her dictionary.
• We didn’t have to make preparations for the quiz.
Need & dare
• Need & dare 既能作实义动词，又能作情态动词。
• Need & dare在肯定句中，通常为实义动词，后面的不定式要带to，单数第三人称加s，有时态
May not & can not may not 译为“可能不”、“也许不会”而非“不可以”。“不可以”为must not或can‘（t 不许，不可以）。
---May I smoke here? ---No, you mustn’t. /you can’t /you can not. The news may not be true. You mustn’t move any of the papers on the desk.
• 情态动词used to表“过去常常做”。往往含有“不再如此”之意。
• Would只能表示动作，不能表示状态。而used to都可以。 .
• He would ask the teacher some strange questions.
• He used to ask the teacher ……
Must have done 对过去事情的肯定猜测
• He must have worked very hard, for he did a good job in the last exam. • They must have had a quarrel. They hadn’t talked with each other for nearly a week. • There must have been a blackout. The whole street was in darkness.
• Had better • Would sooner
• Would as soon • Could
• Might
• Would
• Have to
• Should • Ought to
• Used to • Would rather
• might as well
情态动词问题解析:
may be & maybe
• Need he leave so soon? • You needn’t have done all the heavy work.
• She dare not go home late at night.
• How dare you say I am unfair?
might as well
• might as well译为“不妨”表示规劝。
• We ought not to look down on disabled people.
• Ought we to count on him for the settlement of the debate?
Must
• Must do
• Must be
• Must have done
Must 的反意疑问句
could & may/might have done 表示对过去事情的可能性的推测
（句型Would rather do sth. than do sth. else）
• 表虚拟：would rather sb. did /didn’t do sth.
• I would rather you didn’t do anything for the time being.
Used to & would
Can & be able to
• Be able to 可以表示更多的时态。
• We will be able to finish the work tomorrow.
• He was not able to realize his greatest ambition.
• Are you able to design a new computer program?
• ③“应当”“规定是”可视为情态动词 –be supposed to
• You are to obey the school rules and regulations.
Would rather
• 表意愿：I would rather/sooner not go there on my own.
• 表选择：She would rather die than surrender to the enemy.
• We mustn’t put off the trip no matter what happens.
• We don’t have to put off the trip, although it rains. Must & have to时态的区别
• Must只用于现在 , 而have to则可用于不同时态。用had to表示过去 , 用will have to表示将
education.
• I must help him. {obligation, responsibility} • I have to help him. {unwillingness)
Must & have to的否定
• 否定must 表示“禁止，不允许，一定不要”
• 否定don’t have to 表示“不必,不一定非得,不一定要”
• I must get up at six, ___？
• She must be in the classroom now, _____?
• They must have had great trouble trying to get there, ____?
用 must 提问时的回答
• 肯定回答：must
变化。
• Need & dare作情态动词时，多用于否定句和疑问句。
Examples
• She needs to work even harder if she wants to succeed in her study. • He dares to speak the truth.
• Do you need to take a break? • They didn’t dare to disobey.
be to 可视为情态动词
• be to的三种意义
• ①系表结构
• My duty is instruct students on what is wrong and what is right.
• ②将来时的特殊表达法
• I was to go back home when the phone called.
Modal Verbs 情态动词
情态动词
• 表示说话的语气或情态。情态动词本身有词义，但不完全， 不能单独作谓语， 必须和动词
一起构成谓语。
• 情态动词没有人称和数的变化。
• 大多数情态动词有过去式。
主要情态动词
• Can • May
• Will • Must
• Shall
• Need • Dare