【正文】 于表示理論上的可能性(即從理論上看是可能的，但實際未必會發(fā)生)，或表示“有時”之意。 / could用于表推測的用法(1) 從使用句型上看，can 通常只用于否定句或疑問句，一般不用于肯定句，而could 可用于肯定句、否定句和疑問句。 that C. as。 that C. so。t be late for class.A. so B. so that C. if D. unless( ) 4 We should go by bus ___ we can get there earlier.A. as soon as B. where C. in order that D. as10( ) 1 The dictionary is so expensive ___ I can39。 so B. Though。 so B. If。 than D. /。 as( ) 2 Do you have a big library?No, we don39。 and B. 39。 studied D. are。t go to see the film tonight, because I ___ my ticket.A. lost B. have lost C. will lose D. didn39。 been D. haven39。 have。t see。 was ringing B. were watching。 is bought ,C. was bought。t start the work ___ their teacher came back.A. until B. while C. as soon as D. if2( ) 1 Tom will call me as soon as he ___ Shanghai.A. arrives B. will reach C. arrives in D. get to( ) 2 I39。t be。t。 with D. didn39。 after。t go。 until D. didn39。t start___ everyone was there.A. because B. until C. why D. if( ) 2 The boy ___ to bed ___ his mother came in.A. went not。 until B. didn39。t go。 until。 to C. doesn39。t go。 will be B. isn39。 will be D. won39。m sure he39。 has bought . D. has had。 rang C. watch。 did。 goneC. haven39。t seen。t lose( ) 4 Hello! May I speak to Bob?Sorry, but he ___ for a month.A. had been away B. was left C. left D. has been away( ) 5 I ___ him since I began to live in the city.A. know B. have known C. knew D. will know( ) 6 Zhao Lan ___ already ___ in this school for two years.A. was。 studying5( ) 1 Betty didn39。so。t. At least, not___yours.A. as big as B. as big than C. as bigger than D. bigger as( ) 3 Suzhou is not ____ beautiful ____ Hangzhou.A. as。 than( ) 4 Iron is more useful ___ any other metal.A. as B. than C. then D. so7( ) 1 I want to know ___ she is going to see a film.A. if B. that C. what D. which( ) 2 You are sure to pass the exam ___ you study hard.A. if B. thoughC. that D. since( ) 3 I39。 and C. Though。 but C. As。t buy it.A. because B. when C. that D. if( ) 2 I got there ___ late ___ I didn39。 that D. so。 as D. such。兩者沒有時間上的差別，只是could 比 can 更委婉，更不確定。如：Even experienced teachers can make mistakes. 即使是有經(jīng)驗的教師也可能出錯。He can’t [couldn’t] have understood. 他不可能理解了。如：You could have helped him. 你本來應(yīng)該幫助他的。(1) 在句型使用方面：兩者均可用于肯定句和否定句，但用于疑問句時，may通常不用于句首，但可用于疑問句的句中（如特殊疑問句等），而might盡管可以用于疑問句的句首，但不算普通，通常會改用其他句式（如用could等）。如：He may [might] tell his wife. 他也許會告訴他妻子。如：It was really very dangerous. I might have killed myself. 那真的是太危險了，我差點沒命了。You might at least have answered my letter. 你至少可以回我一封信嘛。No, he must be lying. 不，他一定在撒謊He must have mistaken my meaning. 他一定誤會了我的意思。Look at the time! We should have been at the theatre ten minutes ago. 瞧都什么時候了! 十分鐘前我們就該到戲院了。She needn’t have e in person — a letter would have been enough. 她本不必親自來——寫封信來就足夠了?，F(xiàn)結(jié)合近幾年的高考題目，對表推測的情態(tài)動詞的用法作一歸納，希望對各位考生會有所幫助：【考例】1. Naturally, after I told her what to do, my daughter _____ go and do the opposite! 　　　　　　 A. may B. can C. must D. should (2003年普通高等學校春季招生統(tǒng)一招生考試英語試題（安徽卷）)【分析】Can,may,must都可用來表示”推測”，但側(cè)重點各有不同：May常用來指”事實上的可能性”，而can則表示一種”理論上的可能性”例如：The railways may be improved.=It is possible that the railways will be improved.