情態(tài)動詞講解---最好版精編版

1、 can/could 1. 表示“能力”， 此時could是can的過去式 與be able to 的區(qū)別 can/could 只表示有能力做某事 be able to 表示有能力做并且確實做到了 2. 表示驚異、懷疑、猜測 （多用于否定句和疑問句中） could/can 此時表示語氣強弱或可能性大小。 How can you be so rude? Michael cant be a policeman, for he is much too short. 3. 表示“請求、許可” 翻譯成“可以” 此時could語氣更委婉。 Can/could I use your car tomorrow

2、? You can borrow some books from the library. 4. 有時會，偶爾會 It can be quite cold in May. may/might 1. 表示“請求、許可”， might 語氣更委婉，此時可與could/can 互換 May I ask you for help? 2. may 放到句首時表祝愿 May you succeed!/ May God bless you! 3. 表推測 “也許、可能” He may come here tomorrow. may well do 很可能 may/might as well do 最好，不妨

3、 must 1. “必須” 否定式：mustnt 不應(yīng)該、不許可、不準(zhǔn)、禁止 You must hand in your homework before the class is over. neednt /dont have to “不必” 2. 肯定式表示對現(xiàn)在或過去的推測，“一定” must be doing sth./must have done sth. He must be waiting for us now. He must have seen the film. 3. “非得、偏要” （常用于疑問句/條件狀語從句中） Must I play the piano at home

4、, mum? If you must know, her name is Lucy. must 與have to do 的區(qū)別: must 表示說話人的主觀看法 “必須” have to do 表示客觀上需要，不得不做某事，有人稱、數(shù)和時態(tài)的變化。 shall 1. 用在一、三人稱疑問句中，表示向?qū)Ψ秸髑笠庖?Shall we begin our class? When shall he be able to leave the hospital? 2. 用在第二、三人稱陳述句中，表示說話人給對方的命令、警告、允諾、威脅。 You shall be punished if you keep o

5、n coming to school late. He shall be fired . 3. 根據(jù)某項協(xié)議規(guī)定 “應(yīng)該” You shall bring down the price according to the agreement. should/ought to 1. 表示責(zé)任或義務(wù)上“應(yīng)該” ought to 的語氣更強 should 含有建議、勸告的意味。 2. should 表推測 “應(yīng)該” 3. 竟然 I cant imagine that he should behave so rudely at the party. 4.萬一(if條件從句中)If the compute

6、r should break down, well at the expenses. will/would 1. 表示“請求、建議” would 語氣更委婉 Will/would you please open the door? Would you pass me the book? 2. 表示意愿、意志和決心。 此時would 是will的過去式 I will never do that again. He said he would help us out of trouble. 3. would 表示過去經(jīng)常發(fā)生或習(xí)慣性的動作，“總是” He would go swimming in

7、summer when he lived in the countryside. used to do過去常常但現(xiàn)在已不再 need/dare 情態(tài)、實義動詞 need 必須、需要 （常用于否定和疑問句中） dare 敢 （常用語否定、疑問和條件句中） need to do/dare to do 有人稱、數(shù)和時態(tài)的變化 I dare say 我敢說，我認(rèn)為 情態(tài)動詞+have done 表示推測和虛擬 1. must have done 只用于肯定句中，表示對過去情況肯定的推測 2. should have done _ _ 3. shouldnt have done _ _ 4. can/c

8、ould have done _ _表推測，過去應(yīng)該做了某事表虛擬，過去本應(yīng)該做某事而實際沒有做表推測，過去不應(yīng)該做了某事表虛擬，過去本不應(yīng)該做某事而實際上做了表推測，過去可能做了某事 表虛擬，過去本來有能力/能夠做某事而沒有做 5. cant/couldnt have done _ 6. may/might (not)have done _ _ 7. neednt have done _ didnt need to do would have done 本來會去做表推測，過去不可能做過某事表推測，過去也許/或許(沒)做了某事表虛擬， 過去本可以/可能做某事而實際沒有做本來沒有必要做某事 1.

9、 One of the few things you _ say about English people with certainty is that they talk a lot about the weather. A. need B. must C. should D. can 2. The biggest problem for most plants, which _ just get up and run away when threatened, is that animals like to eat them. A. shant B. cant C. neednt D. mustntDB 3. He didnt regret saying what he did but felt that he _ it differently. A. could express B. would express C. could have expressed D. must have expressed 4.