情态动词表推测课件.ppt
ModalVerbs,must,can,could,will,would,may,might,should,ought to,mustmaymight（could）can,could 一般用于否定句和疑问句中cant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cant,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 cant 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,isnt 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。Cant“一定不”，can在疑问句中意思是“会、可能”。He cant 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 Nings.It has her name on it。The guitar belong to Alice.She plays the guitar.,2.否定句中用cant/couldnt(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.must,2.That man must be Sarahs husband.-No,he_ be her husband.She is still single.A.cant B.mustnt C.may not D.ought to3.Peter _come with us tonight,but he isnt 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;cant;must B.can;can;mustC.can;mustnt;must D.must;mustnt;can5.Look,someone is coming.Guess_.-Jack.Hes always on time.A.who can it be B.who he mayC.who he can be D.who it can be,6.David,you _play with the valuable bottle,you_ break it.A.wont;cant B.mustnt;mayC.shouldnt;must D.cant;shouldnt,7.Sue_ come together with us tonight,but she isnt very sure yet.A.must B.may C.need D.will,
