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高中英语语法系列情态动词定义：情态动词表示说话人对某一动作或状态的态度。
特点：有一定词义；不受主语人称和数的变化影响；与主要动词的原形一起构成谓语。
情态动词：can/could ; may/might; must ;need ;will/would ; shall /should ; dare / dared ;used to ; ought to etc情态动词的基本用法1. can/coulda. 表能力，could 主要指过去时间1) Two eyes can see more than one .2) The girl could read before she went to school .* be able to do 意思同can/could ,但有较多时态表达形式；在表达过去某个事件有能力干什么时，could 表虽有能力，但不一定做了；was able to 指“不但有能力，而且实际做了”。
3) He _______ escape from the fire , but he went to save the girl .( could /was able to )4) Though the fire spread quickly , everyone ________ escape . ( could /was able to )b. 表可能5) The man there can’t be Mr. Zhang . He has gone to Nanjing .6) Look ! Someone is coming ! Who can it be ?7) * The temperature can fall to – 60 °C8) * He can make mistakes sometimes though he is clever .c. 表允许9) ---Can / Could I use your pen ?--- Yes , you can ./ Sure , go ahead . ( Yes , you could 错误 )d . 表惊异，怀疑，不相信等态度（用于否定句，疑问句或感叹句中）10) Can this be an excuse for being late ?11) No , no , this can’t be true .12) How can you be so careless!2. may / mighta. 表允许13) --- May / Might I ask you for a photo of your baby ?--- Yes , please . / Certainly ./ Please don’t ./ You’d better not ./ No , you mustn’t.b. 表可能，might 语气更加不肯定14) She may be at home .15) She might come to the party , but I am not sure .c .祝愿16) May you succeed !3 . musta . 表义务，意为“必须”，主观意志；而have to 为“不得不”，客观要求。
情态动词分类情态动词是英语中一类特殊的动词形式，用来表示说话者的态度、推测、建议、命令等。
在英语语法中，情态动词属于情态助动词的一种，具有一些特殊的用法和语法规则。
本文将分类介绍情态动词的用法和特点。
一、情态动词的基本特征情态动词有一些共同的特征，包括：1. 情态动词没有人称和数的变化，与主语保持一致；2. 情态动词后面跟动词原形，不加其他形式的动词；3. 情态动词后面不加“to”，用于表示动作或状态的情态动词与动词原形连用；4. 情态动词不能单独充当谓语，必须与其他动词连用形成谓语。
二、情态动词的分类及用法根据其不同的用法，情态动词可以分为以下几类：1. 表示能力和可能性的情态动词- Can：表示能力，意为“能够”；- Could：表示过去的能力或请求的委婉方式；- May：表示可能性，以及征求许可的委婉方式；- Might：表示较小的可能性或提出建议；- Shall：表示应该，常用于疑问句；- Should：表示应该，用于陈述句、建议或推荐；- Will：表示意愿，以及将来的行动或事件；- Would：表示过去的习惯或委婉的请求。
2. 表示允许和禁止的情态动词- Must：表示必须，用于肯定句和疑问句；- Have to：表示必须，用于陈述句和疑问句；- Need to：表示需要。
3. 表示推测和假设的情态动词- Must：表示强烈的推测；- May/might：表示可能性；- Can't/couldn't：表示否定的推测；- Should：表示推测或建议。
4. 表示意愿和目的的情态动词- Would：表示意愿、建议或委婉的请求；- Shall/will：表示意愿、请求或承诺；- Should：表示意愿、目的或建议。
5. 表示要求和命令的情态动词- Shall：表示命令或要求；- Should：表示命令或建议；- Must：表示强制性的要求。
6. 表示习惯和义务的情态动词- Must：表示必须遵守的规定或义务；- Should：表示习惯或预期的行为。
高中英语语法之情态动词（一)情态动词的定义:情态动词表示说话人对某一动作或状态的态度。
（二）情态动词的特点:1)有一定词义；2）不受主语人称和数的变化影响；3)与主要动词的原形（或称不带to的不定式）一起构成谓语（除ought to作固定词组看待)。
情态动词无人称和数的变化, 情态动词后面跟的动词需用原形，否定式构成是在情态动词后面加”not"。
个别情态动词有现在式和过去式两种形式，过去式用来表达更加客气, 委婉的语气，时态性不强, 可用于过去,现在或将来。
情态动词属非及物动词,故没有被动语态。
He could be here soon。
他很快就来。
We can’t carry the heavy box。
我们搬不动那箱子。
除此之外，情态助动词还有如下词法和句法特征：1）除ought和used以外，其他情态动词后面只能接不带to的不定式.We used to grow beautiful roses. I asked if he would come and repair my television set.2）情态助动词在限定动词词组总是位居第一： They need not have been punished so severely。
3）情态助动词用于第三人称单数现在时的时候,没有词形变化,即其词尾无—s形式：She dare not say what she thinks。
4）情态动词没有非限定形式，即没有不定式和分词形式，也没有相应的动名词：Still， she needn't have run away。
5）情态助动词的“时”的形式并不是时间区别的主要标志。
在不少场合,情态助动词的现在时和过去时形式都可以表示现在、过去或将来时间：Would you mind very much if I ask you to do something？ She told him he ought not to have done it。
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。
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。
高中英语语法总结大全之情态动词情态动词的语法特征1）情态动词不能表示正在发生或已经发生的事情，只表示期待或估计某事的发生。
2）情态动词除ought 和have 外，后面只能接不带to 的不定式。
3）情态动词没有人称，数的变化，即情态动词第三人称单数不加-s。
4）情态动词没有非谓语形式，即没有不定式，分词，等形式。
比较can 和be able to1）cancould 表示能力；可能 (过去时用could),只用于现在式和过去式(could)。
be able to可以用于各种时态。
They will be able to tell you the news soon. 他很快就能告诉你消息了。
2）只用be able toa. 位于助动词后。
b. 情态动词后。
c. 表示过去某时刻动作时。
d. 用于句首表示条件。
e. 表示成功地做了某事时，只能用was/were able to，不能用could。
He was able to flee Europe before the war broke out.= He managed to flee Europe before the war broke out.注意：could不表示时态1）提出委婉的请求，（注意在回答中不可用could）。
--- Could I have the television on?--- Yes, you can. / No, you can't.2）在否定，疑问句中表示推测或怀疑。
He couldn't be a bad man.他不大可能是坏人。
比较may和might1）表示允许或请求；表示没有把握的推测；may 放在句首，表示祝愿。
May God bless you!He might be at home.注意： might 表示推测时，不表示时态。
只是可能性比may 小。
2）成语： may/might as well，后面接不带to 的不定式，意为"不妨"。
高中英语知识点归纳情态动词和实义动词的用法情态动词和实义动词是高中英语中常见的两类动词，它们具有不同的用法和含义。
下面将对情态动词和实义动词的用法进行归纳总结。
一、情态动词的用法情态动词是表示说话人的语气、态度、情感等方面的动词，常用的情态动词有can，could，may，might，must，shall，should，will，would等。
情态动词的用法如下：1. 表示能力和技能：- can 和 could 表示能力，主要用于肯定句和疑问句中。
- can 用于现在和将来时，could 用于过去时。
- She can swim.（她会游泳。
）- Could you play the guitar?（你会弹吉他吗？）2. 表示许可和禁止：- can 和 may 表示许可，可以用于肯定和疑问句中。
- cannot 和 must not 表示禁止。
- You can go now.（你现在可以走了。
）- May I use your phone?（我可以用一下你的手机吗？）- You must not smoke here.（你不能在这里抽烟。
）3. 表示推测和可能性：- may，might 和 could 表示可能性，可用于肯定和疑问句中。
- may 和 might 可用于现在和将来时，could 可用于过去时。
- He may come tomorrow.（他明天可能来。
）- Could it be true?（这可能是真的吗？）4. 表示义务和建议：- must 和 have to 表示义务，表示说话人的主观意愿。
- should 和 ought to 表示建议或期望。
- We must finish our homework.（我们必须完成作业。
）- You should see a doctor.（你应该去看医生。
）二、实义动词的用法实义动词是指具有实际意义的动词，用来表示具体的动作、状态或变化。
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”。
情态动词知识点情态动词（Modal Verbs）是英语中的一类特殊动词，用于表示说话人的态度、观点、意愿、能力、推测等。
了解和正确使用情态动词对学习英语语法和提高语言表达能力非常重要。
本文将介绍情态动词的基本知识点，包括定义、用法及常见情态动词的具体用法和表示的含义。
一、情态动词的定义和用法情态动词是一类特殊的助动词，常用的情态动词有can、could、may、might、must、shall、should、will、would等。
情态动词有以下几个特点：1. 情态动词本身没有词义，不能单独用作谓语，后面需加动词原形来构成句子。
2. 情态动词本身没有人称和数的变化。
3. 情态动词没有时态的变化，表示的是一种情态或态度，并不表示动作的时间或进行的状态。
情态动词主要用于以下几个方面的功能：1. 表示能力和可能性：can、could、may、might、must；2. 表示推测和可能性：may、might、could；3. 表示意愿和请求：will、would、shall、should；4. 表示命令和建议：shall、should、will、would；5. 表示义务和必要性：must、should。
二、常见情态动词的具体用法和含义1. can/could:- 表示能力、技能：I can speak English fluently.- 表示允许：Can I use your computer?- 表示请求：Could you please help me carry this bag?- 表示推测：He could be at home.2. may/might:- 表示允许、请求、建议：May I come in? Might I suggest a different approach?- 表示推测、可能性：She may be busy. It might rain later.- 用于虚拟语气：If I had more time, I might go on vacation.3. must:- 表示必须、肯定：You must follow the rules.- 表示推测、非常有可能：He must be tired.- 表示责任、命令：You must finish the report by tomorrow.4. shall/should:- 表示建议、意愿、命令：Shall we go for a walk? You should see a doctor.- 表示期望、推测：The train should arrive soon.5. will/would:- 表示意愿、决心：I will help you with the project.- 表示请求、邀请：Would you like to join us for dinner?- 表示推测、意愿、假设：She would probably be upset if you didn't go.三、注意事项1. 情态动词后面的动词原形不带to。
十一.情态动词情态动词表示说话人的语气和情态。
如需要、可能、愿意、怀疑等。
情态动词有一定的词义，但不完整，必须和主要动词的原型一起构成谓语。
常用的情态动词有：can, could, may, might, must, have to, ought to, need, dare, shall, will, should, would, be able to,及半情态动词be to do, had better等。
情态动词的基本用法：（一）can“能够”1.表示体力或脑力方面的能力，或根据客观规律能做某事的能力。
如：He can speak English. I can go there now.表“能够”时，既可指现在也可指将来。
(2)can与be able to的区别：①表“能力”时二者同义No one can / is able to do it.② be able to常侧重经过努力有能力做到，有多种时态。
can侧重自身的能力，只有一般现在时和一般过去时。
③ was / were able to do 表示通过努力克服困难或在一定的条件下成功地做了某事，侧重结果，相当于managed to do 或succeeded in doing...。
could仅表自身的能力或本领，但未必成功做到。
With the help of the firemen, they were able to leave the burning house.He was able to swim across the river.In the end, we were able to rescue the workers trapped in the fire.2.表示“许可，允许”。
在疑问句中表示请求，许可；否定句中表示“不许”。
此时常与may通用：May/Can I do it?This sort of thing can't这类事情不能再继续了！not有时可以表示“禁止”相当于mustn't：You can't（mustn't，are not allowed to）play football in the street.你不可以在大街上踢球。
3.表示推测，强调客观可能性：“可能、会”。
主要用于疑问句和否定句。
表示推测、估计时，后边可根据不同情况用动词原形、进行式、完成式。
Who can he be?She can't be waiting for you.He can't have gone there alone.4.表惊讶、疑虑。
How can it be that he was late for the opening ceremony?他咋会连开幕式都迟到？Can it be late? 会不会晚了？（二）could1．表“能力”“可能性”“许可”，为can的过去式。
He said he could go.2. could用于一般现在时中表委婉、客气地提出问题或陈述看法。
（此时不是can的过去式，要用can回答以显得爽快。
此时can和could没有时间的差别，只是could语气更客气些。
）-Could I borrow your pen? - Yes, you can.（三）may, might (may的过去式为might）1.表示许可，有“可以”的意思，询问或说明一件事可不可以做，有时可以用can互换。
You may go now.否定式may not表示“不可以、禁止、阻止”等，常用must not （＝mustn't）代替。
may用于疑问句中时，回答多避免用may，以免显得太严肃或不客气。
-May I watch TV tonight？ -Yes, you can.（No, you mustn't/you'd better not）-May I smoke here？-Yes, please.(No, please don't.)2.表推测：“或许、可能”。
表示一件事或许会发生，只用在陈述句中。
It may rain tomorrow.3. may可以表祝愿，一般放在句首构成倒装句式：May you succeed! =I hope you may succeed.祝您成功!May that day come soon! 希望这一天早日来到！May you be happy, healthy and wealthy!祝你快乐，健康，富有。
4. might是may的过去式，表可以做的事或可能发生的事。
She suggested a few books which I might buy.5. might用于一般现在时比may委婉，或表示现实的可能性更小一些。
He might come soon.I wonder if I might borrow some coffee？6. may (just) as well, might as well.“不妨…”（可以用来提出建议）。
它们比had better 显得谦逊或不那么有把握，所以had better通常是不用于长者或上司的。
同时，had better有时带有威胁口吻。
（may well为“完全能；满可以；很可能”，表示有可能或有充分理由做某事。
well是may的程度副词）I needn't wait; I may as well tell you now.我不必等，我不妨现在就告诉你。
Since it's a fine day, we might as well walk.既然是好天气，我们一不妨走走。
You may well say so.你完全有理由这么说。
It may well be that the question is still under discussion.那很可能是该问题仍在讨论中。
●had better是固定词组，亦可说had best，用来表示一种很有把握的建议和劝告，意思是“最好…”。
①现代英语中常用better代替had better, 有时省主语：You had better be careful. = You better be careful. = Better be careful.②had better后接be doing结构时，表示立即做某事。
I think I'd better be going.我想我最好马上走。
③had better接完成式表示对过去本该做而没做的事的遗憾。
You'd better have come earlier.你本该早点来。
7. may, may not, might + be doing也表猜测，译为“可能，正在或可能不在干…”She may not be doing such silly things.He may be doing his work. （四）must1.表示必须要做的事，意为“必须”，否定式mustn't表示不准、不许、禁止等。
在回答带有must 的问句时，不用mustn't，而用needn't或don't have to。
I must go now.We mustn't waste our time.Must I go home? No ，you needn't. / Yes, you must. 2. must 在表“必须”时与have to 相近，have to 强调客观需要，must 着重主观看法。
另外must 不像have to 能有更多的时态。
You must be back by ten.（命令或叮嘱） You have to be back by ten.（客观需要） 3.表推测，暗含很大的可能性，意为“一定、肯定”，只用于“肯定句”中。
此时其否定式为can't,“绝非”。
He must be over sixty. There must be a mistake. 4.偏偏、硬要、干嘛（指做令人不快的事） The car must break down just when we were about to start off. 我们正要出发的时候偏偏车坏了。
Must you shout so loudly? 你干嘛这么大声喊？ （五）shall 1.表示命令、履行义务、意愿、许诺、警告、强制、威胁、决心等，一般用于二、三人称中，并用于陈述句。
You shall have my answer tomorrow.（允诺） You shall be sorry for it one day, I tell you.（警告） You shall do as I tell you.（命令或吩咐）We shall go, whatever may happen.（决心） I shan ’t speak with her.（决心） You shall clean theclassroom this afternoon.(义务) He shall give you your own money.(威胁) ※2. shall 表示愿意，用在疑问句中，用于二人称表示征询听话人是否愿意，但多用will 。
Shall you go with me? 3.征求听话人意见和指示，用在一、三人称的疑问句中。
Shall I turn on the light ？ Shall he come to see you? ＝Do you want him to see you? （六）should should 是shall 的过去式，但它同时又是一个有单独意义的情态动词。
1.表达职责、义务，作“应当”讲，常与ought to 互换。
但ought to 侧重反映客观情况，should 侧重表示主观看法。
2.表示预测可能性，并译作“可能，（按道理）应该”。
They should come here now.3.用于委婉、谦逊地提出意见或建议。
I should think you are right.我以为你是对的。
4. should用于某些从句中表虚拟语气：①用于表示建议、命令的动词的宾语从句中。
表示建议、命令的动词有suggest（表“建议”时）, advise（忠告）, recommend（推荐）, order（命令）, demand(要求）urge（力劝）,require(要求）, request(请求）,desire （渴望）, ask / insist（表“坚决要求”含义时）等词的宾语从句的谓语应由“should+动词原形”构成，此时should可省略。
