1、原形原形过去式过去式词义词义句型变化（否定句一般在其后加句型变化（否定句一般在其后加 ，一般疑问句将其提到，一般疑问句将其提到 ）may You may take a walk after supper.（肯定）（肯定）否定：否定：一般疑问句：一般疑问句：can I could swim at the age of seven.（肯定）（肯定）否定：否定：一般疑问句：一般疑问句：must We must arrive home before 10:00.（肯定）（肯定）否定：否定：一般疑问句：一般疑问句：have to Tom had to go home on foot last night
2、.（肯定）（肯定）否定：否定：一般疑问句：一般疑问句：shall Students should be allowed to play computer games.（肯定）（肯定）否定：否定：一般疑问句：一般疑问句：need 注意：注意：need 作情态动词只用于疑问句和否定句中。作情态动词只用于疑问句和否定句中。Need I close all the windows？（一？（一般疑问句）般疑问句）否定：否定：had better You had better stay at home.（肯定）（肯定）否定：否定：【知识回顾】not句首mightmight可以，或许可以，或许You may
3、 not take a walk after supper.You may not take a walk after supper.May I take a walk after supper?May I take a walk after supper?couldcould能够，可以能够，可以I couldnt swim at the age of seven.I couldnt swim at the age of seven.Could you swim at the age of sevenCould you swim at the age of seven？/一定，必须一定，必须W
4、e neednt(dont have to)arrive home before 10:00.We neednt(dont have to)arrive home before 10:00.Must you arrive home before 10:00Must you arrive home before 10:00？had tohad to不得不不得不Tom didnt have to go home on foot last night.Tom didnt have to go home on foot last night.Did Tom have to go home on foo
5、t last nightDid Tom have to go home on foot last night？shouldshould应该应该Students shouldnt be allowed to play computer games.Students shouldnt be allowed to play computer games.Should students be allowed to play computer gamesShould students be allowed to play computer games？/需要需要You neednt close all
6、the windows.You neednt close all the windows./最好最好You had better not stay at home.You had better not stay at home.知识点一：情态动词情态动词在句子中不能单独作谓语，只能和其他动词连用作谓语，表示说话人的语气和情感。主要的情态动词有：_，_，_，_，_，_，_，_，_，dare等。1.情态动词表推测：部分情态动词可以用来表示推测，推测的可能性由小到大为：cant（不可能）mightmay（可能）could can（可能）（can用于疑问句）must（一定）2.使用情态动词要注意以下方
7、面：(1)含must的一般疑问句：肯定回答仍用must，否定回答则用_或_，表示“不必”。一般不能用 ，(2)may开头的一般疑问句：肯定回答用may或can，否定回答用_。例如：May I smoke here?No,you mustnt.【要点梳理】needntdont have tomustntmustnt/cantcanmaymustneedwouldshouldought tocouldmight2.使用情态动词要注意以下方面：(3)表示可能性或推测时：can多用于否定句或疑问句，cannot表示“_”；may多用于陈述句，may not表示“可能不”；must只用于肯定句，表示“_
8、”。(4)need用作情态动词：主要用于否定句、疑问句和条件句，表示“_”，也可以作实义动词，后跟名词、代词、不定式、动词-ing形式等。need开头的一般疑问句，肯定回答用must。You neednt come if you are busy.如果忙，你就不必来了。（_ 动词）He needs to get some sleep.（动词）不可能一定需要情态实义need to do sth 【例题】（）1.Where is our head teacher,Mr.Black?He be in the office.I saw him there a minute ago.A.can B.ma
9、y C.might D.cant（）2.Is that your best friend Simon?No,it be him.He flew to Hong Kong yesterday.A.mustnt B.may not C.cant D.neednt【举一反三】（）3.I borrow these magazines?Sorry,only the magazines over there can be borrowed.A.Must B.Would C.May D.Need（）4.you swim?Yes,but I am not a good swimmer.A.Can B.May
10、C.Need D.Must知识点二：情态动词should&shouldntShould为情态动词，意为“应该”，后接动词原形，其否定形式为 ，变为一般疑问句时，should提到_。例如：1.You should give it a try.2.You shouldnt do things like that.其用法如下：(1)表示委婉地提出意见或建议时，意为“_”。You should brush your teeth before you go to bed.(2)表示义务，责任时，意为“应该，应当”。You should help your mother with your housewo
11、rk.We should study hard.(3)表示命令或要求时，语气比较强烈。You shouldnt go out at night.shouldnt句首应该，应当(4)should与ought to（ought to 表示处于责任，义务，道义等方面的要求而该做的事）在多数情况下，ought to 和should 两者意义相同在与其上不同一些而已。肯定句：Students should study hard.=Students ought to study hard 否定句：Students shouldnt study hard.=Students _ study hard.疑问句
12、：Should students study hard?=_ students_ study hard？Yes,they should./No,they shouldnt.=Yes,they ought to./No,they _.Ought toought not toought not to【典型例题】（）1.You _ drive your car so fast.Its very dangerous.A.wouldnt B.shouldnt C.couldnt D.mightnt （）2.We teenagers _ have dreams.With dreams and hard w
13、ork,anything amazing can be created.A.may B.must C.should D.might 【举一反三】（）3.I wasnt sure whether I _ offer to help or not.A.should B.might C.would D.needed（）4.Youre making so much noise in the library!You _ come here.A.should B.shouldnt C.will D.need 知识点三：情态动词could1.can（1）表示体力或脑力方面的“能力”，也能表示根据客观条件能做
14、某事的“能力”。如：He can drive.can与be able to二者都表示“能够”，区别是：can只有现在时和过去式，而be able to可用于各种时态。如：如：Ill be able to speak French in half a year.（2）表示允许：You can go now.（3）表示推测：Who can it be?can表示猜测或怀疑只用于疑问句及否定句中。2.could（1）can的过去式，表示过去有能力及过去的可能性。He couldnt climb up the mountain.（2）表示客气地请求或委婉地陈述意见。Could you go skati
15、ng with me tomorrow?（3）表示惊异、怀疑、不相信等态度。How could he say that?can 有能力，不一定能做到；be able to有能力，一定做得到【例题】（）1.you swim?Yes,but I am not a good swimmer.A.Can B.May C.Could D.Must（）2.you give me that book？Thanks！A.Can B.Could C.Should D.Shall【举一反三】（）3.His son walk when he was two years old.A.can B.is able to
16、C.could D.may（）4.Is Sue singing in the next room?It be her.She cant sing English songs at all.A.may B.can C.cant D.Must【小结】一、单选题。1._ I go out to play now，Mum?No，you_ AMay，shouldnt BCan，neednt CMust，cant DMaymustnt2.Help me with this case,_ you?Adont Bwill Cdo Dshall3.They started early that morning
17、in order that they_ there before noon Amight get Bmay get Cwould get Dgot 4.A teacher do every exercise，but a pupil_ Aneednt，must Bmay not，must Cneednt,neednt Dcant,must5.If you _ do as I tell you，you_ go to the party Acan，shant Bwill,wont Cwont，shall D wont,shant 6.I talked for a long time，and in t
18、he end I_ make her believe me Acould Bcan Cmust Dwas able to7.Dont believe himHis story _ be true Amustnt Bneednt Cshouldnt Dmay not8.-She must have gone back to the valley -No,she _.The entrance to it was nowhere to be found Amustnt Bneednt Ccouldnt Dhadnt 9.You need not do it at once,_?Aneednt you Bmustnt you Cdont you Dneed you 10.He must be in the classroom,_ he?Amustnt Bcant Cisnt Dcan
