课件17张PPT。 ModalVerbsmust, can, could, will, would, may, might, should, ought tomust>may>might(could)
can, could 一般用于否定句和疑问句中can’t一定不,是must的否定句情态动词 can, could, may,might,must表推测的用法: 情态动词中的can, could, may, might, must都表推测。其中must的可能性最大,can / could次之,may / might最小。具体用法如下:1. must的用法(1)表示推测“可能性”时,意思是“一定、准是”,语气较肯定,较有把握。He must be American. = It is certain that he is American. 他准是个美国人。(2)must表推测只能用于肯定句。
如表示“一定不、肯定不”的意思时,改为否定用can`t,
如询问某种可能时,应用can。He must know my address. 他肯定知道我的地址。
(一定) He can`t know my address. 他肯定不知道我的地址。
(一定不)Can he know my address? 他知道我的地址吗?
(询问可能性)(3)must表示推测时,可以推测现在/正在发生的动作
He must have a car now. (现在)他一定有辆小汽车。He must be doing his exercises in the classroom.(正在进行)他一定在教室里做练习。(4)在反意疑问句中,当附属部分含有表示推测意义的must时,疑问部分的助动词应与must后面的动词在非推测情况下的用法保持一致。
He must be a worker, isn`t he? (现在)他准时个工人,是吗?
2. can / could的用法(1)can表示推测“可能性”时,往往用于否定句或疑问句。Can`t“一定不”,can在疑问句中意思是“会、可能”。He can`t be at home. = It is impossible that he is at home. 他一定不在家。(3)could 还可以用于表示客气、委婉、礼貌的请求语气。
Excuse me, could you tell me the way to the bus station?Could you help me?
3. may和might的用法(1) may, might表示推测“可能性”时,意思是“可能”、“也许”He may / might be American. = It is possible that he is American.他可能是个美国人。注:might不表示过去时态,只是语气上比may更委婉,表示的可能性更小。(2)may, might表推测时,可以用于否定句,意思是“可能不、也许不”,但不用于疑问句。He may / might not be at home. 他也许不在家。情态动词表推测的三种句式 1.在肯定句中一般用must (一定),may(可能),might / could(也许,或许)。
It ——— be Ning’s. It has her name on it 。
T he guitar ———— belong to Alice. She plays the guitar.
2.否定句中用can’t / couldn’t(不可能), may not/might not(可能不)。
(1)It ______ be the headmaster. He has gone to America
(2)He ————know the scientist. 他也许不认识那位科学家。 3.疑问句中用can/could (能……?)。 (1)—————— he finish the task? 他可能把任务完成吗? (2)———— he be at home now? 他现在能在家吗? Choose the best answers :1. I thought you______ like something to read. So I have brought you some books. A. ought B. might
C. would D. must2. –That man must be Sarah’s husband.--No, he_____ be her husband. She is still single.A. can’t B. mustn’t
C. may not D. ought to
3. Peter _____come with us tonight, but he isn’t very sure.A. must B. may C. can D. will 4. –What____ it be?--It______ be a mail box, for it is moving.
It______ be a car.A. can; can’t; must B. can; can; mustC. can; mustn’t; must D. must; mustn’t; can
5. –Look, someone is coming. Guess__________ .--Jack. He’s always on time.A. who can it be B. who he mayC. who he can be D. who it can be6. David, you _____play with the valuable bottle, you_______ break it.A. won’t; can’t B. mustn’t; mayC. shouldn’t; must D. can’t; shouldn’t7. Sue________ come together with us tonight, but she isn`t very sure yet. A. must B. may
C. need D. will