情态动词的基本用法归纳

1、情态动词的基本用法归纳时间：2021.03.07创作：欧阳德情态动词有 can (could), may (might), must, have to, shall (should, will (would), dare (dared), need (needed), ought to等。情态动词无人称和数 的变化；不能单独使用，必须与其后的动词原形构成 谓语。、can, could1) 表示能力(体力、知识、技能)。Can you lift this heavy box?(体力)Mary can speak three Ionguages.(知识)Can you skate?(技能)此时可用

2、be able to代替。Can只有一般现在 时和一般过去式；而be able to则有更多的时态。I' II not be able to come this aft emo on.当表示“经过努力才得以做成功某事”时应用be able to,不能用 Carlo 如:He was able to go to the party yesterday evening in spite of the heavy roin.2) 表不请求和允许。Con I go now?Yesz you can. / Noz you con' t.此时可与may互换。在疑问句中还可用 could,m

3、ight代替，不是过去式，只是语气更委婉， 不能用于肯定句和答语中。Could I come to see you tomorrow?Yes, you can. （ No, I' m afraid not.）3）表示客观可能性（客观原因形成的能力）。They' ve changed the timetable, so we can go by bus instead.This hall can hold 500 people at least.4）表示推测（惊讶、怀疑、不相信的态度），用 于疑问句、否定句和感叹句中。Can this be true?This con'

4、t be done by him.How can this be true?二、may, might1）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canJ t或 mustnJ t,表示“不可以，禁止”。Might/ May I smoke in this room?Noz you mustn' t.May/Might I take this book out of the room?Yesz you con. （No, you ccin' t / mustn5 t.） 用May I.?征徇对方许可时比较正式和客气，而 用Canl.?在口语中更常

5、见。2）用于祈使句，表示祝愿。May you succeed!3）表示推测、可能性（不用于疑问句）。might不是过去式，它所表示的可能性比may 小。1. He may /might be very busy now.2. Your mother may /might not know the truth.三、must, have to1）表不必须、必要。You must come in time.在回答引出的问句时，如果是否定的，不能用 mustn, t （禁止，不准），而用 needn, t, don' t have to （不必）一一 Must we hand in our e

6、xercise books today?Yes, you must.Noz you don, t have to / you neednJ t.2) must是说话人的主观看法，而have to则强 调客观需要。Must只有一般现在时，have to有更多 的时态形式。1. he play isnJ t interesting, I really must go now.2. I had to work when I was your age.3) 表示推测、可能性(只用于肯定的陈述句)1. You' re Tom, s good friend, so you must know wh

7、at he likes best.2. Your mother must be waiting for you now.四、dare, need1) dore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daredo1. How dare you say I' m unfair?2. He daren5 t speak English before such a crowd, dare he?3. If we dared not go there that day, we couldn' t get the beautiful flowers.2) need作

8、情态动词用时，常用于疑问句、否定 句。在肯定句中一般用 must have to, ought toz should 代替。1. Youneedn' t come so early.2. Need I finish the work today?Yes, you must. / No, you needn5 t.3) dare和need作实义动词用时，有人称、时 态和数的变化。在肯定句中，dare后面常接带to的 不定式。在疑问句和否定句中，dare后面可接带to 或不带to的不定式。而need后面只能接带to的不 定式。1.1 dare to swim across this riv

9、er.2. He doesn, t dare (to) answer.五、shall, should1) 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。1. You shall fail if you don, t work hard警告)2. He shall have the book when I finish it.(允诺)3. He shall be punished威肋、)六、will would1）表示请求、建议等，would更委婉。Will / W

10、ould you pass me the ball, please?2）表示意志、愿望和决心。1.1 will never do that again.2. They asked him if he would go abroad.3）would表示过去反复发生的动作或某种倾向。 would表示过去习惯时比used to正式，且没有“现 已无此习惯”的含义。1. During the vacation, he would visit me every other day.2. The wound would not heal.4）表不估计和猜想。It would be about ten o&

11、#39; clock when she left home.七、should, ought to1）should, ought to 表示“应该”，ought to 表 示义务或责任，比should语气重。1.1 should help her because she is in trouble.2. You ought to take care of the baby.2）表示劝告、建议和命令。should, ought to可 通用，但在疑问句中常用shouldo1. You should / ought to go to class right away.2. Should I open

12、 the window?3）表不推测should , ought to （客观推测）,must（主观推测）。1 .He must be home by now.（断定他已到家）2. He ought to/should be home by now不太 肯定）3. This is where the oil must be.（直爽）4. This is where the oil ought to/should be含 蓄）八、情态动词+不定式完成式（have done）1） can / could + have done在肯定句中表示“本来可以做而实际上能做某事”，是虚拟语气；在 疑问句或否

13、定句中表示对过去行为的怀疑或不肯定，表 示推测。1. You could have done better, but you didn, t try your best.（虚拟语气）2. He canJ t have been to that town.（推 测）3. Can he have got the book?（推测）2) may / might + 不定式完成式(have done)表示对过去行为的推测。不能用于疑问句中，没 有虚拟语气的用法。Might所表示的可能性比may 小。1. He may not have finished the work .2. If we had t

14、aken the other road, we might have arrived earlier.3) must +不定式完成式(have done)用于肯定句中，表示对过去行为的推测。意为 “一定、想必”。其疑问、否定形式用can, canJ t 代替。参看1) can / could + have done表示推测。1. You must have seen the film Titanic.2. He must have been to Shanghai.4) should + 不定式完成式(have done)用于肯定句中，表示对过去行为的推测。He should have finished the work by now。表示“本应该做而实际上没有做某事”，其否定 式表示某种行为本不该发生却发生了。可以与ought 忆+不定式完成式(have done)互换。1. You ought to / should have helped him. (but you didn' t.)2. She shouldn' t have taken away my measuring tape, for I wa