高中英语语法讲解： 情态动词
高中英语知识点归纳情态动词和实义动词的辨析与用法总结
高中英语知识点归纳情态动词和实义动词的辨析与用法总结情态动词和实义动词是英语中常见的两种动词形式，它们在用法和含义上有着一些区别。
了解并正确使用这两种动词形式对于学习英语语法和提高语言表达能力非常重要。
本文将对情态动词和实义动词的辨析与用法进行总结和归纳。
一、情态动词的定义和特点情态动词（Modal Verbs）是一类具有一定语法和词义特征的动词，它们可以用来表示说话人对某种动作、状态或可能性的判断、意愿、能力、推测等。
情态动词有以下几个特点：1. 情态动词没有人称和数的变化，不用于同主语的动词之间的语态和时态的变化。
例如：can, could, may, might, shall, should, will, would, must等。
2. 情态动词后面接动词原形，不加不定式to。
例如：Can you swim?（你会游泳吗？）3. 情态动词后面的动词原形表示动作的完成或否定形式。
例如：She can't swim.（她不会游泳。
）4. 情态动词可以用于构成疑问句、否定句和肯定句。
例如：Could you help me?（你能帮助我吗？）He can't come to the party.（他不能来参加派对。
）You must be careful.（你必须小心。
）5. 情态动词在句中起到了"助动词"的作用，帮助说明说话人的意图、态度和推测等。
例如：You should study hard.（你应该努力学习。
）He must be at home.（他一定在家。
）二、实义动词的定义和特点实义动词（Main Verbs）是表达实际动作或状态的动词，它们具有人称和数的变化，可以接不定式、动名词、名词等作宾语，并且可以根据需要进行时态和语态的变化。
实义动词有以下几个特点：1. 实义动词可以根据主语的人称和数的不同进行变化。
例如：Iwalk to school.（我走路去上学。
高中英语语法讲义-情态动词
He may [might] be writing a letter. 他可能在写信。
They may [might] be going abroad next month. 他们可能在下个月出国。
③ 后接动词完成式，表示对过去可能发生的事进行推测：
另外，could还可与表示感知的动词(如see, hear, smell, taste, feel, understand等)连用表示的特定能力：
Looking down from the plane, we could see lights on the runway. 从飞机上向下看，我们可以看见机场跑道上的点点灯火。
2) 表示委婉的批评或责备：
You might have made greater progress. 你的进步本来可更大一些的。
You might at least have answered my letter. 你至少可以回我一封信嘛。
③ 表示“差点儿就要”：
I could have died laughing. 我差点儿笑死了。
二、may与might的用法
1. 表示允许
注意以下两种情况：
(1) 表示请求允许(即请求别人允许自己做某事)，两者都可用，只是 might 表示的语气较委婉(但并不表示过去)：
May [Might] I sit here? 我可以坐在这里吗?
1) 表示过去某事可能发生而实际上却并没发生：
A lot of men died who might have been saved．很多人本来可以获救的却死了。
It was really very dangerous. I might have killed myself. 那真的是太危险了，我差点没命了。
高中英语知识点归纳情态动词和一般现在时的否定和疑问句总结
高中英语知识点归纳情态动词和一般现在时的否定和疑问句总结情态动词 (Modal Verbs) 是英语中一类特殊的动词形式，用来表示说话人对某种行为或状态的态度、推测、可能性、必要性、能力等。
一般现在时的否定句 (Negative Sentences in Simple Present Tense) 是用来陈述某种情况或事件常态发生的句子形式，表达否定的意思。
一般现在时的疑问句 (Interrogative Sentences in Simple Present Tense) 是用来询问某件事情是否发生或存在的句子形式，表达疑问的意思。
以下是对高中英语中情态动词及一般现在时的否定和疑问句的归纳总结：一、情态动词 (Modal Verbs) 的用法：1. 可能性 (Possibility)：- can- could- may- might2. 推测 (Speculation)：- must- should- may/might3. 必要性 (Necessity)：- must- have to- need to- should4. 动词表示能力 (Ability)：- can- could- be able to5. 动词表示许可 (Permission)：- can- could- may- might6. 动词表示请求 (Request)：- can- could- will7. 动词表示允诺 (Promise)：- will- shall- would8. 动词表示建议 (Advice)：- should- ought to- had better二、一般现在时的否定句 (Negative Sentences in Simple Present Tense)：1. 在一般现在时的肯定句中，在动词前加上助动词 "do" 或 "does"，并加上 "not" 以构成否定句。
情态动词高中知识点高三
情态动词高中知识点高三情态动词是一类具有特殊意义和用法的动词，它们在句子中一般与实义动词连用，表示说话人的推测、命令、请求、建议等情态。
在高中英语学习中，掌握情态动词的正确用法至关重要。
本文将介绍情态动词的相关知识点，帮助高三学生更好地运用这一语法现象。
一、情态动词的定义情态动词，又称情态助动词，是用来表示说话人对某种动作或状态的态度、推测、可能性、能力、意愿、义务等情态的一类特殊动词。
常见的情态动词包括can、could、may、might、must、shall、should、will、would等。
二、情态动词的用法1. 表示能力情态动词can表示某人具有能力或可能做某事，could用于过去说法。
例如：- She can speak three languages fluently.（她能说流利的三种语言）- He could lift the heavy boxes when he was younger.（他年轻时能搬起这些沉重的箱子）2. 表示推测和可能性情态动词may、might、could用于表示推测和可能性。
may用于表示较为肯定的推测，might和could表示推测的可能性较小。
例如：- The weather is cloudy, it may rain later.（天气多云，可能会下雨）- He might be late for the meeting.（他可能会迟到会议）3. 表示义务和建议情态动词must表示说话人对某种行为具有强烈的责任感或坚决要求，should表示建议。
例如：- We must obey the laws of the country.（我们必须遵守国家的法律）- You should apologize to your friend for your mistake.（你应该为你的错误向朋友道歉）4. 表示许可和请求情态动词can、may、could用于表示允许和请求。
情态动词知识点总结高中
情态动词知识点总结高中情态动词是英语中一个重要的语法现象，它们能够表达说话者的情感、态度、意愿等，以及表达说话者对事件的推测、猜测、可能性等。
了解情态动词的用法，能够帮助我们更准确地表达自己的意思，也有助于我们理解他人的意图。
本文将对情态动词的概念、用法、以及常见的情态动词进行总结和归纳，以便于读者更深入地理解情态动词的使用。
一、情态动词的概念情态动词（Modal Verb）是一类特殊的助动词，用来表示说话者的情感、态度、意愿等，以及表达说话者对事件的推测、猜测、可能性等。
情态动词通常用于句子的前面，后面跟动词原形，用来构成不同的语法结构和表达不同的含义。
英语中常见的情态动词有can、could、may、might、must、shall、should、will、would、ought to等。
这些情态动词具有一些共同的特点，比如不能独立完成谓语，后面必须跟动词原形；在疑问句和否定句中，情态动词的位置要发生变化等。
二、情态动词的用法1. 表示能力和可能性can与could表示说话者的能力或者对某种事情的可能性，其中can用于现在时，could用于过去时。
比如：I can speak Spanish.（我会说西班牙语。
）She could swim when she was five.（她五岁的时候就会游泳。
）may与might也表示可能性，may 用于现在时，might 用于过去时。
比如：It may rain tomorrow.（明天可能会下雨。
）I thought she might come.（我以为她可能会来。
）2. 表示请求和建议will与would可以表示请求，will用于肯定句，would用于否定句和疑问句。
比如：Will you please help me?（你能帮帮我吗？）I would like to go with you.（我想和你一起去。
）shall与should也可以表示请求或者建议，should更多地表示建议。
高中英语语法——情态动词总结(附带练习)
情态动词总结I 情态动词的特征：1.本身有词义。
2.不能独立作谓语。
2. 后接动词原形一起构成谓语。
3. 不随人称和数的变化。
II 情态动词各自的基本意义及用法：1.大多数情态动词（除表‘能力、许可、意志’外），都可以表示推测，其程度有差异。
按可能性程度的高低排列为：must﹥will ﹥would ﹥ought to ﹥should完全肯定完全可能很可能﹥can ﹥could﹥may ﹥might可能有可能2. 区分情态动词的否定含义：may not或许不、可能不might not可能不can’t 不可能mustn’t不许、禁止shouldn’t不应该needn’t 不必1.情态动词表推测的反意疑问句，简单来说，就是以情态动词后的时态为淮，如句子里有明确的时间状语，则以其为准。
2.以must 为例：E.g. 1. You must be hungry now, aren’t you?2. He must be watching TV , isn’t he ?3 Tom must have lived her for a long time, hasn’t he ?4. She must have arrived yesterday, didn’t she?注：如选择题中（以She must have arrived yesterday, didn’t she？为例）既有didn’t she又有hasn’t she则以didn’t she？为最佳答案。
IV 情态动词专项练习与解析一( ) 1. You _____ return the book now. You can keep it till next week if you like.A. can’tB. mustn’tC. needn’tD. may not( ) 2. Where is my pen? I _____ it.A. might loseB. would have lostC. should have lostD. must have lost( ) 3. I wish I _____ you yesterday.A. seenB. did seeC. had seenD. were to see( ) 4. I didn’t hear the phone. I _____ asleep.A. must beB. must have beenC. should beD. should have been( ) 5. If my lawyer _____ here last Saturday, he _____ me from going.A. had been; would have preventedB. had been; would preventC. were; would preventD. were; would have prevented( ) 6. He _____ you more help, even though he was very busy.A. might have givenB. might haveC. may have givenD. may give( ) 7. If it _____ for the snow, we _____ the mountain yesterday.A. were not; could have climbedB. were not; could climbC. had not been; could have climbedD. had not been; could climb( ) 8. Without electricity human life _____ quite difficult today.A. isB. will beC. would have beenD. would be( ) 9. A computer _____ think for itself, it must be told what to do.A. can’tB. couldn’tC. may notD. might not( ) 10. Jenny _____ have kept her word. I wonder why she changed her mind.A. mustB. shouldC. needD. would( )11. We _____ last night, but we went to the concert instead.A. must have studiedB. might studyC. should have studiedD. would study( ) 12. — Could I borrow your dictionary?— Yes, of course you _____.A. mightB. willC. canD. should( ) 13. Tom ought not to _____ me your secret, but he meant no harm.A. have toldB. tellC. be tellingD. having told ( ) 14. — If he _____, he _____ that food.— Luckily he was sent to the hospital immediately.A. was warned; would not takeB. had been warned; would not have takenC. would be warned; had not takenD. would have been warned; had not taken ( ) 15. Peter _____ come with us tonig ht, but he isn’t very sure yet.A. mustB. mayC. canD. will( ) 16. I told Sally how to get here, but perhaps I _____ for her.A. had to write it outB. must have written it outC. should have written it outD. ought to write it out( ) 17. I didn’t see your sister at the meeting. If she _____, she would have met my brother.A. has comeB. did comeC. cameD. had come ( ) 18. — Shall I tell John about it?—No, you _____. I’ve told him already.A. needn’tB. wouldn’tC. mustn’tD. shouldn’t ( ) 19. When a pencil is partly in a glass of water, it looks as if it _____.A. breaksB. has brokenC. were brokenD. had been broken( ) 20. It’s nearly seven o’clock. Jack _____ be here at any moment.A. mustB. needC. shouldD. can( ) 21.— There were already five people in the car but they managed to take me as well.— It _____ a comfortable journey.A. can’t beB. shouldn’t beC. mustn’t have beenD. couldn’t have been ( ) 22. Johnny, you _____ play with the knife, you _____ hurt yourself.A. won’t; can’tB. mustn’t; mayC. shouldn’t; mustD. can’t; shouldn’t ( ) 23. The fire spread through the hotel very quickly but everyone _____ get out.A. had toB. wouldC. couldD. was able to ( ) 24. — When can I come for the photos? I need them tomorrow afternoon.— They _____ be ready by 12:00.A. canB. shouldC. mightD. need( ) 25. — I stayed at a hotel while in New York.— Oh, did you? You _____ with Barbara.A. could have stayedB. could stayC. would stayD. must have stayed ( ) 26. — Will you stay for lunch?— Sorry, _____. My brother is coming to see me.A. I mustn’tB. I can’tC. I needn’tD. I won’t( ) 27. — Are you coming to Jeff’s party?—I’m not sure. I _____ go to the concert instead.A. mustB. wouldC. shouldD. might( ) 28. — Write to me when you get home.— _____.A. I mustB. I shouldC. I willD. I can( ) 29. I was really anxious about you, you _____ home without a word.A. mustn’t leaveB. shouldn’t have leftC. couldn’t have leftD. needn’t leave( ) 30. — Is John coming by train?— He should, but he _____ not. He likes driving his car.A. mustB. canC. needD. may专项练习（二）1. I didn’t see her in the meeting room this morning. She _____ at the meeting.A. mustn’t have spokenB. shouldn’t have spokenC. needn’t have spokenD. couldn’t have spoken2. One ought _____ for what one hasn’t done.A. not to be punishedB. to not be punishedC. to not punishedD. not be punished3. If you really want yourself to be in good health, you must ___ always ___ so much.A. not; be smokingB. not; have smokedC. not; to smokeD. be not; smoking4. With so much work on hand, you _____ to see the game last night.A. mustn’t goB. shouldn’t goC. couldn’t have goneD. shouldn’t have gone5. Most of the students felt rather disappointed at the English party. They say that it ______ better organized.A. had beenB. had to beC. must have beenD. could have been6. I’m surprised that he _____ in the exam.A. should failB. would have failedC. may have failedD. should have failed7. The little girl _____ there alone.A. not dare goB. dares not goC. dare not goD. dare not to go8. “Must we do it now?” “No, you _____.”A. won’tB. needn’tC. can’tD. don’t9. He said he would rather not _____ it right now.A. doingB. to doC. doD. to be doing10. You _____ to the meeting this afternoon if you have something important to do.A. needn’t to comeB. don’t need comeC. don’t need comingD. needn’t come11. Put on more clothes. You _____ be feeling cold with only a shirt on.A. canB. couldC. wouldD. must12. I _____ play football than baseball.A. would ratherB. had betterC. like betterD. prefer13. I thought you _____ like something to read, so I have brought you some books.A. mayB. mightC. couldD. must14. There was plenty of times. She _____.A. mustn’t have hurriedB. couldn’t have hurriedC. must not hurryD. needn’t have hurried15. The plant is dead. I _____ it more water.A. will giveB. would have givenC. must giveD. should have given16. You _____ return the book now. You can keep it till next week if you like.A. can’tB. mustn’tC. needn’tD. may not17. It’s still early, you _____.A. mustn’t hurryB. wouldn’t hurryC. may not hurryD. don’t have to hurry18. Please open the window, _____?A. can’t youB. aren’t youC. do youD. will you19. We _____ for her because she never came.A. mustn’t have waitedB. shouldn’t have waitedC. mustn’t waitD. needn’t wait20. — May I stop here? — No, you _____.A. mustn’tB. might notC. needn’tD. won’t21. It’s a fine day. Let’s go fishing, _____.A. won’t weB. will weC. don’t weD. shall we22. I didn’t see her in the meeting room this morning. She _____ at the meeting.A. mustn’t have spokenB. shouldn’t have spokenC. needn’t have spokenD. couldn’t have spoken23. — Please don’t make a noise. — _____. I’ll be as quiet as a mouse.A. Yes, I won’tB. No, I won’tC. No, I willD. Yes, I will24. The young man has made so much noise that he _____ not have been allowed to attend the concert.A. couldB. mustC. wouldD. should25. — Where is John? — He _____ in the library.A. should beB. must beC. can beD. must have been26. Since the road is wet this morning, _____ last night.A. it must rainB. it must be rainingC. it must have rainedD. it must have been rain27. — Will your brother stay home tonight?— I’m not quite sure. He _____ to the cinema tonight.A. must goB. can goC. may goD. may be going28. She’s already two hours late. What ______ to her?A. can have happenedB. may have happenedC. should have happenedD. must happen29. You must be a writer, _____?A. mustn’t youB. are youC. must youD. aren’t you30. I got up early that morning, but I _____ so because I had no work to do.A. mustn’t have doneB. didn’t need to doC. needn’t have doneD. can’t have done31. He _____ have come here yesterday, but he didn’t.A. couldB. shouldC. ought toD. all the above32. I missed the last bus, so I _____ go home on foot.A. mustB. have toC. mayD. had to33. He ought to win the first prize, _____ he?A. oughtn’tB. shouldn’tC. mustn’tD. both A and B34. Everyone _____ do his best for the modernizations of our country.A. canB. mayC. shouldD. might35. Let’s clean our classroom, _____?A. will youB. don’t weC. shall weD. do you36. Let us play basketball, ______?A. will youB. don’t weC. shall weD. do you37. He asked me for this book many times. Please tell him that he _____ have it tomorrow.A. mustB. mayC. shallD. both B and C38. “Your phone number again? I _____ quite catch it.” “It’s 9568442.”A. didn’tB. couldn’tC. don’tD. can’t39. Mother _____ us stories when we were children.A. was used to tellB. is used to tellingC. used to tellD. used to telling40. She would rather _____ more money on books _____ on clothes.A. cos t … notB. to spare … don’tC. pay … thanD. spend … than专项练习（三）1. — Has Li Lin started? He said he would join in the party.— He ______. He is a man of keeping his word.A. could have leftB. must have leftC. can’t comeD. won’t be c oming2. — May I park my car here?— No, you ______. No car is allowed to park here.A. may notB. needn’tC. mustn’tD. daren’t3. — Excuse me, could you tell me where the Yajia Supermarket is?—It’s two blocks straight ahead. You ______ miss it.A. mustn’tB. can’tC. needn’tD. shouldn’t4. — I saw Mr. Sun at Tongyu Station this morning.—You ______. He’s still on holiday in Hawaii.A. couldn’t haveB. mustn’t haveC. shouldn’tD. needn’t5. — How about paying a visit to Dr. Wang, our former Chinese teacher?— Good idea. I will e-mail him today so that he ______ know ______ to expect us.A. shall; whyB. could; whenC. would; whatD. will; how6. Everything has two sides. Beautiful songs, sometimes, ______ be just noise to others.A. mustB. mayC. shouldD. could7. Someone ______ my umbrella. I found it wet yesterday.A. must be usingB. must have usedC. must useD. must have been using8. — How dangerous it was!— Yes, but for the passer-by’s quick action, th e girl ______.A. was drownedB. could have been drownedC. had drownedD. should be drowned9. You ______ scold such a pupil who always keeps silent so seriously that you ______ hurt him.A. should; canB. may; willC. mustn’t; mayD. can’t; must10. — Why does Alice know so much about Angkor Wat?— She ______ have been there, or ...A. mustB. oughtn’t toC. mayD. can’t11. —You may laugh, but I’ve been thinking of becoming a vegetarian.— Oh, you ______ be crazy. You will be hungry all the time.A. mustB. mayC. willD. need12. —What’s the matter with you?—Oh, I’m not feeling well in the stomach. I ______ so much fried fish just now.A. shouldn’t eatB. mustn’t have eatenC. shouldn’t have eatenD. mus tn’t eat13. — ______ he have been chosen as captain of the football team?— Yes, he ______.A. Can; must haveB. Must; must haveC. Can; mustD. Must; must14. Mr. Zhang ______ in Shanghai tomorrow morning.A. can have arrivedB. will have arrivedC. may have arrivedD. must have arrived15. Miss Wang started at 8 o’clock, and she ______ be there now.A. shouldB. canC. can’tD. need16. — It must be Mr. Li who did it. — No, it ______ be Mr. Li.A. mustn’tB. wouldn’tC. can’tD. may17. You ______ finish reading the book as soon as possible.A. mayB. canC. needD. should18. — Need you go to work now? — Yes, I ______.A. mustB. needC. canD. dare19. Your trousers are dirty. ______ them for you?A. Shall I washB. Will I washC. Am I going to washD. Am I washing情态动词专项练习与解析一【练习解析】1．C 从原题中You can keep it till next week if you like这一信息句可知，“你不必现在还”。
高中英语知识点归纳情态动词和现在完成时的否定和疑问句总结
高中英语知识点归纳情态动词和现在完成时的否定和疑问句总结情态动词及现在完成时的否定和疑问句总结情态动词（Modal Verbs）和现在完成时（Present Perfect Tense）是高中英语中的重要知识点，它们在语法和语义上都有一定的特点和用法。
本文将对情态动词和现在完成时的否定和疑问句进行总结和归纳。
一、情态动词的基本用法情态动词是一类特殊的助动词，常用的情态动词包括can、could、may、might、shall、should、will、would、must等。
情态动词具有以下几个基本用法：1. 表示能力、可能性和允许性例如：- I can swim.（我会游泳。
）- It may rain tomorrow.（明天可能会下雨。
）- You can't smoke here.（这里不允许吸烟。
）2. 表示推测和猜测例如：- He must be tired.（他一定累了。
）- She might be at home.（她可能在家。
）- They couldn't have known about it.（他们不可能知道这件事。
）3. 表示义务和建议例如：- Students should wear uniforms to school.（学生们应该穿校服上学。
）- You must finish your homework before going out.（你必须在出去之前完成作业。
）二、现在完成时的构成和基本用法现在完成时表示过去发生的动作对现在造成的影响或结果。
它由助动词have/has加上过去分词构成，其中have用于第一人称和第二人称，has用于第三人称单数。
现在完成时的基本用法如下：1. 表示过去开始并延续到现在的动作或状态例如：- I have lived in this city for five years.（我在这个城市住了五年了。
）- They have been friends since childhood.（他们从小就是朋友。
高中英语语法系统讲解之八情态动词和虚拟语气
高中英语语法系统讲解之八情态动词和虚拟语气情态动词一. 情态动词的类型和特征1. 类型○1只作情态动词用的有：can（could），may（might），must，ought to。
○2可作情态动词也作实义动词的有：need，dare。
○3可作情态动词也作助动词的有：shall（should），will（would）。
○4具有情态动词某些特征的有：have（had）to，used to。
2. 特征情态动词有一定的词义，但不能单独作谓语，须和实义动词或系动词连用，构成谓语；且适用于主语的各种人称和数（have to例外），主语是第三人称单数时，要用has to。
二. 情态动词的基本用法1. can与could○1○2表示惊异、推测、怀疑、不相信的态度（主要用于否定句、疑问句中）。
如This can’t be done by him.○3can的习惯用法A. can but的用法can but“只好，至多不过”，如We can but do our best.B. cannot help but，cannot help的用法二者都表示“不得不；不能避免；不禁”；但前者后加动词原形，后者加代词或动名词等。
如The girl couldn’t help but live on herself.When I try to speak, I can’t help making mistakes.C. cannot … too“无论怎样……都不过分；越……越好”如We can’t thank you too much for what you have done for us。
We can not be too careful to cross the road.温馨提示：○1can与be able to：can表示有能力做某事，be able to表示通过努力、克服困难做成某事。
如Although his leg was hurt, he was able to swim to the bank.I believe I can work it out all by myself. ○2could与be able to：could表示过去一般的能力，即不表示做与未做某事，而was / were able to表示有能力做并且成功地做了某事，相当于managed to do sth / succeeded in doing sth。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
高中英语语法讲解：情态动词概述1.共有10个情态动词：can/could, may/might, will/would, shall, should, ought to, must；2个半情态动词need, dare2.特点：（1）情态动词后加动词原形（即不带to的不定式）一起构成谓语；（2）没有人称和数的变化；（3）多数情态动词有过去式，但其过去式有时并不表示时态，而只起“委婉或不确定语气”的作用。
Would you do me a favour? She may/might be watering the flowers now.3.情态动词在句子中可发挥不同作用，如表能力，表责任与义务，表推测，表征求允许，表请求，表建议，表语气态度等等He can/could run 100 meters in 11 seconds.You should/ought to/must work hard to win a gold medal.Can/Could/May/Might I watch the Olympics tonight?Will/Can/Could/Would you help me with my training?He might/may/could/should/ought to/will/must watch the football match tonight.I suggest that you should watch the opening ceremony.Can this be true?4.情态动词+do 表对一般现在或将来情况的推测情态动词+ be doing 表对正在发生的事情的推测情态动词+have done 表对过去已经发生的事情的推测一、can/could 的用法1.表能力(1) can do现在一般的能力(2) could do过去一般的能力(3) could have done过去有能力做但没做具体某事（4）was/were able to do = managed to do/ succeeded in doing 过去有能力做且做了具体某事。
注：be able to可用于各种时态、不定式中或其他情态动词之后I can speak fluent English now, but I couldn't (不能)ten years ago.He could have fled (flee)the city before the war broke out, but he stayed with his sick wife.You could have done the work better, but you were too careless.The fire spread through the hotel quickly but everyone was able to get out.2．表示请求和允许。
(could更委婉，但答语中须用can)--Can / Could I use your computer? --Yes, of course you can. / No, I’m afraid you can't.3.表推测(1) can在肯定句+现在时中，表示理论上的可能性，对某件宽泛的事情而言，并不表示具体某事是否会发生，可译为“有时会，理论上可能”。
注：若要表示具体某事发生的可能性，要用could, may, might。
More accidents can happen on such rainy days.A wise man can make mistakes.It can be as hot as 40℃ here in summer.Baby are lovely, but sometimes they can be tiresome.Peter could/may/might come with us tonight, but he isn’t sure yet.(2) can/could在否定句和疑问句中，可表示某事实际发生的可能性，译为“可能(吗)”，“不可能”。
Listen, someone is coming. Can/Could it be Tom?My wallet is nowhere to be seen. Who can/could have taken it away?It is 10 o'clock in the morning. Tom can't/couldn't be sleeping now. 不可能正在做某事The streets are all dry. It can't/couldn't have rained last night. 过去不可能已经做某事4.固定用法：(1) can not/never…too/enough“再怎么…也不过分，越…越好”I can never thank you enough. You can't be too careful.You can never remember too many words.(2) can't + 比较级“不能更...，非常...”I can't agree more. The film couldn't' t be more boring(3) cannot but do sth. 不得不，只好I cannot but admire your bravery.(4) can't help doing sth 情不自禁做；can't help (to) do sth 不能帮忙做二、may/might的用法1．表示请求和允许，译为“可以”。
might更委婉，否定回答可用may not/ can't/ mustn't。
--May/Might I use your pen? --Yes, you may./--No，you may not/ can't/ mustn’t．2．表推测, 表具体某事实际发生的较小的可能性；否定句中may/might not 译为“可能不”--Are you coming to Jeff’s party? --I’m not sure. I might go to the concert instead.She may/might not know he is a millionaire.3．may表示祝愿或希望。
May God bless you! May you return in safety！May we never forget each other！4.固定搭配：(1) may well do sth很可能Her appearance has changed so much that you may well not recognize her.(2) may/might as well do sth 最好You may as well tell me the truth. We may as well stay where we are.(3) may/might have done①可能已经做了某事（表推测）She isn’t here. She may/might have missed the first train in the morning.He hasn’t come. He may/might not have finished the work.②本来可能做，但实际没有做（含轻微责备语气）You should not have climbed the tree. You might have hurt yourself.You might have given him more help, even though you were busy.三、must 的用法1.表示责任与义务，译为“必须，一定”，否定mustn't表示“禁止，不允许”注：表示“不需要，不一定”用needn’t或don’t have toYou must finish the task within three days.The book is wonderful. You simply must read it.You needn't/don't have to watch the match if you don’t want to.You mustn't smoke here. There are patients in this room.-- Must we hand in our exercise books today?--Yes，you must/ No, you needn't/ don't have to．注：区别于have to：must 多表示主观自愿，而have to表示客观被迫，且有时态变化。
The play is not interesting．I really must go now．To support myself, I had to work when I was your age．2.表固执态度，与别人的意愿相违背，译为“偏要、偏偏、非要”--How old are you, madam?-- If you must know, I’m twice your age.Jane must do the opposite of her parents.Must you make so much noise at such a late hour?When we were just going to have a vacation, our son must have a fever.3. 表推测，肯定句中，表具体某事实际发生的极大的可能性，译为“想必，一定”；否定句中，表“不可能”用can’t，不用mustn'tHe must be rich. He must be waiting for us.The lady can't be (不可能是) only 30. She must be(准是) over 50.4. must have done表示对过去已经发生的事情进行推测，意为“一定已经做了某事”。
He must have finished his essay. Otherwise, he wouldn't go to see the film.5. must后面反意疑问句的用法：(窍门= I am sure that 从句)You have worked hard all day. You must be tired, aren't you?He must be working in his office, isn't he?You must have learned English for many years, haven't you?You must have stayed up late last night, didn't you?It must have rained, hasn't it?It must have rained last night, didn't it?四、shall的用法（否定shall not = shan't）1.疑问句中，当主语为第一、第三人称时，表示征求对方意见或请求指示Shall we go out for a meal tonight?Shall he/they come to see you tomorrow?Let’s meet at the school gate tonight, shall we?2.陈述句中，当主语为第二、第三人称时，表示允诺，警告，威胁，命令。