有些情态动词，如can， could， may， might， must， ought to， should 后面可以接动词的完成形式，表示对已经发生的事的猜测或对应该发生的事的看法。

　　They shouldn’t have left so soon.

　　They must have been through a lot.

　　I needn’t have told them that.

　　He can’t have left for Shanghai for I saw him a moment ago.

　　How could you have forgotten such an important thing？

　　They must have arrived by now.

　　You oughtn’t to have done that.

　　She looks so miserable. You oughtn’t to have hurt her feelings.

　　“I was late yesterday because my car broke down. ”（broke的原型是break，这里表抛锚的意思） “You should have borrowed mine. I wasn’t using it. ”

　　情态动词部分除了应了解每个词的具体含义之外，情态动词的否定是在后面加not.特别要注意had bette和would rather的否定。ought to的否定是ought not to.would rather后面接句子只能用一般过去时。can、could、may、might、must、ought to、should后接动词完成式表示对过去事情的猜测。

　　“may/might + 现在完成时”表示“也许已经……了”；

　　“must + 现在完成时”表示“肯定……了”；

　　“can / could + 现在完成时”表示“本来是能够……的（实际上未）”；

　　“should/ought to + 现在完成时”表示“本应该……（实际上未）”。

　　1、That was in March. You may / might have read about it in the newspapers.

　　2、The house is dark； the Browns _______ to bed.

　　A. may go B. should go C. should have gone D. must have gone

　　（答案 D）

　　3、Her husband could have helped her， but he chose not to.（choose）

　　4、You _______ yesterday if you were really serious about the job.

　　A.ought to come B. ought come C. ought to have come D. ought have come

　　（答案 C serious 严肃的）

　　此外，考生还应注意need和dare这两个词，它除了是情态动词外，还可以是实义动词，在不同的情况下用法有差别

　　1、To travel from England to Scotland you _______ a passport.

　　A. mustn’t have B. haven’t got C. don’t need D. needn’t

　　（情态动词后要接动词原型 答案 C）

　　2、The house needs ________， but they plan to wait until next spring to do it.

　　A. paint B. to paint C. painting D. be painted

　　（答案 C）

　　1、“Do you have to leave？”

　　“Sorry ， but I really _____.”

　　A. have B. had to C. do so D. must

　　答案 D

　　2、I want to go to the dentist， but you ________ with me.

　　A. needn’t to go B. needn’t go

　　C. don’t need go D. need go

　　neen’t为情态动词，后接动词原型

　　don’t need为实义动词，后面接to

　　答案 B

　　3、“______ you pass me the salt？”

　　“Sure. Here you are .”

　　A. Might B. Must C. Could D. Need

　　答案 C

　　4、“I haven’t felt well for a week.”

　　“You ______ see a doctor.”

　　A. have ought ot B. had better

　　C. should have to D. would rather

　　答案 B

　　5、“Doesn’t Elaine want to see that movie？”

　　“Yes， but she says _______ go tonight.”

　　A. she’ll rather not B. she’d rather not

　　C. she’d not rather D. she won’t rather

　　would rather的否定词放在rather的后面，动词的前面。

　　答案 B

　　6、“Listen， Mary is singing in the next room.”

　　“That ______ be Mary. She’s in hospital.”

　　A. may not B. shouldn’t C. should have gone D. can’t

　　答案 D

　　7、John ______ a restless person. He kept moving from country to country.

　　A. must be B. should go C. must have been D. must have gone

　　答案 C

　　8、I can’t find Tom anywhere. I think he ____ to the library.

　　A. may go B. must go C. must have gone D. should have gone

　　should have gone 应该……而实际上没……

　　答案 C

　　9、“What’s the matter with that picture on the wall？”

　　“It needs _________.”

　　A. straightening B. to be straightening C. straightened D. straighten

　　答案 A

　　10、“Tom graduated from college at a very young age.”

　　“He _________ an outstanding student.”

　　A. must be B. could be C. must have been D. should have been

　　对过去推测，情态动词后接现在完成时。

　　答案 C

　　11、The old lade needs ________ after her shock.

　　A. to comfort B. comforting C. to be comforted D. Both B and C

　　答案 D