21.14 比较need和dare
 
  这两词既可做实义动词用,又可做情态动词用。作为情态动词,两者都只能用于疑问句,否定句和条件句。 need 作实义动词时后面的不定式必须带to,而dare作实义动词用时, 后面的to 时常可以被省略。
1) 实义动词: need (需要, 要求)
        need + n. / to do sth
2) 情态动词: need,只用原形need后加do,否定形式为need not。
  Need you go yet? 
  Yes, I must. / No, I needn't.
3) need 的被动含义:need, want, require, worth(形容词)后面接doing也可以表示被动: 
  need doing = need to be done
21.13 带to 的情态动词
 
  带to 的情态动词有四个:ought to, have to, used to, be to, 如加上have got to ,(=must), be able to,为六个。它们的疑问,否定形式应予以注意:
  Do they have to pay their bill before the end of the month?
  She didn't use to play tennis before she was fourteen.
  You ought not to have told her all about it.
  Ought he to see a heart specialist at once.?

  ought to 本身作为情态动词使用。其他的词作为实义动词使用,变疑问,否定时,须有do 等助动词协助。

典型例题
 Tom ought not to ___ me your secret, but he meant no harm.  
 A.have told B.tell C.be telling D. having told
 答案A。由于后句为过去时,告诉秘密的动作又发生在其前因,此地应用过去完成时,但它在情态动词 ought to 后,所以用have。
 

21.11 will和would
 
 注意: 
 1)would like; Would like to do = want to 想要,为固定搭配。
   Would you like to go with me?
 2)Will you…? Would you like…? 表示肯定含义的请求劝说时,疑问句中一般用some, 而不是any。
   Would you like some cake?
 3)否定结构中用will,一般不用would, won't you是一种委婉语气。
   Won't you sit down?
21.12 情态动词的回答方式
 
   问句   肯定回答    否定回答
Need you…?  Yes, I must.   No,I needn't
Must you…?           /don't have to. 

典型例题
1)---Could I borrow your dictionary?
  ---Yes, of course, you____.  
  A. might B. will  C. can  D. should
  答案C.could表示委婉的语气,并不为时态。答语中of course,表示肯定的语气,允许某人做某事时,用can和 may来表达,不能用could或might。复习: will 与you连用,用来提出要求或下命令。should与you 连用,用来提出劝告。

2)---Shall I tell John about it?
  ---No, you ___. I've told him already.  
  A. needn't  B. wouldn't  C. mustn't  D. shouldn't
  答案A。needn't 不必,不用。 wouldn't 将不, 不会的。 mustn't 禁止、不能。 shouldn't 不应该。本题为不需要,不必的意思,应用needn't。

3)---Don't forget to come to my birthday party tomorrow.
  ---______.
  A. I don't  B. I won't  C. I can't D. I haven't 
  答案B. will既可当作情态动词,表请求、建议、也可作为实义动词表"意愿、意志、决心",本题表示决心,选B。

 

21.10 would rather表示"宁愿"
 
 would rather do
 would rather not do
 would rather… than…  宁愿……而不愿。

 还有would sooner, had rather, had sooner都表示"宁愿"、"宁可"的意思。

 If I have a choice, I had sooner not continue my studies at this school.
 I would rather stay here than go home. = I would stay here rather than go home.


典型例题
----Shall we go skating or stay at home?
----Which ___ do?      
A. do you rather  B. would you rather  C. will you rather  D. should you rather
答案B。本题考查情态动词rather的用法,would rather +do sth 意为"宁愿",本题为疑问句,would 提前,所以选B。