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1、情态动词,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。,一、 can, could,1. 表示能力（体力、知识、技能）。 Can you lift this heavy box?（体力） Mary can speak three languages.（知识） Can you skate?（技能） 此时可用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。 Ill not be able to come this afternoon.,当表示“经过努力才得以做成功某事”时应用be able to，不能用Can。如： He
2、 was able to go to the party yesterday evening in spite of the heavy rain.,2.表示请求和允许。 -Can I go now? - Yes, you can. / No, you cant. 此时可与may互换。在疑问句中还可用could, might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, Im afraid not. ),3. 表示客观可能性（客观原因形成的能力）。 Theyve c
3、hanged 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 cant be done by him. How can this be true?,1) - I think Miss Gao must be in the library. She said she would go there. - No. She _ be there, I have j
4、ust been there. A. cant B. mustnt C. neednt D. wouldnt 2) 【2015浙江】It was so noisy that we hear ourselves speak. A. couldnt B. shouldnt C. mustnt D neednt,3.（2014北京卷）_ I have a word with you? It wont take long. A. Can B. Must C. Shall D. Should 4) （2014大纲卷）Although you _ find bargains in London, its
5、not generally a cheap place to shop. A. should B. need C. must D. can,5)（2011浙江卷）- Hows your new babysitter? - We _ ask for a better one. All our kids love her so much. A. should B. might C. mustnt D. couldnt 6) （2008福建卷）It is usually warm in my hometown in March， but it _ be rather cold sometimes.
6、A. must B. can C. should D. would,7)Mr Bush is on time for everything How it be that he was late for the opening ceremony？ (上海2001春) Acan Bshould Cmay Dmust 8) Could I borrow your dictionary？ Yes, of course you (MET92) Amight Bwill Ccan Dshould,9)The fire spread through the hotel very quickly but ev
7、eryone get out(NMET97) Ahad to Bwould Ccould Dwas able to,二、 may, might,1.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cant 或mustnt表示 “不可以，禁止”。 -Might/ May I smoke in this room? - No, you mustnt. - May/Might I take this book out of the room? - Yes, you can. 用May I.？征徇对方许可时比较正式和客气，而 用Can I.？在口语中更常见。,2. 表示推
8、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。 He may /might be very busy now. Your mother may /might not know the truth. 3.用于祈使句，表示祝愿。 May you succeed,1)【2015陕西】You feel all the training a waste of time, but Im a hundred percent sure later youll be grateful you did it. A. should B. need C. shall D. may 2
9、) （2014江西卷）30. Life is unpredictable ; even the poorest _become the richest . A. shall B. must C. need D. might,3)（2008四川卷） Although this _ sound like a simple task，great care is needed。 A. must B. may C. shall D. should 4) Is John coming by train？ He should, but he not He likes driving his car (NME
10、T2002) Amust Bcan Cneed Dmay,5)Are you coming to Jeffs party？ Im not sure I go to the concert instead (NMET2000) Amust Bwould Cshould Dmight 6) Johnny, you play with the knife, you hurt yourself (NMET96) Awont; cant Bmustnt; may Cshouldnt; must Dcant; shouldnt,三、 must, have to,1.表示必须、必要。 You must co
11、me in time. 在回答引出的问句时，如果是否定的，不能用 mustnt（禁止，不准），而用neednt, dont have to（不必）. - Must we hand in our exercise books today? - Yes, you must. - No, you dont have to / you neednt.,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。 I really must go now. I had to work when I was your age,3.表示
12、推测、可能性（只用于肯定的陈述句） Youre Toms good friend, so you must know what he likes best. Your mother must be waiting for you now. 4.偏要,一定要 -May I smoke in the classroom? -Yes, if you must.,1)【2015北京】Cant you stay a little longer? Its getting late. I really _go now, My daughter is home alone. A .may B .can C .
13、 must D .dare 2) 【2015重庆】12. You _ be Carol. You havent changed a bit after all these years. A. must B. can C. will D. shall,3) )【2015四川】You _be careful with the camera. It costs! A .must B. may C. can D. will 4) -Who is the girl standing over there? - Well, if you _know, her name is Mabel. A. may B
14、. can C. must D. shall,5)Some aspects of a pilots job _ be boring, and pilots often _work at inconvenient hours. (湖南卷) A. can; have to B. may; can C. have to; may D. ought to; must 6) - May I smoke here ? (山东卷) - If you _, choose a seat in the smoking section. A. should B. could C. may D. must,四、 sh
15、all,1.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。 You shall fail if you dont work hard.(警告) He shall have the book when I finish it.(允诺) He shall be punished.(威胁),3.用于第三人称疑问句，表示征求意见。,Shall he have a try？,1)Whats the name? Khulaifi. I spell that for you ? (北京卷) A. Shall B. Would C. Can D .Might 2) -What does the sign over there read? - “No person _ smoke or carry a lighted cigarette，c
