Unit 5 Discovering Useful Structures （ppt课件）-2022新人教版（2019）《高中英语》必修第三册.pptx

1、UNIT 5 THE VALUE OF MONEYSection C Discovering Useful Structures 单元语法 情态动词基本特征1.情态动词本身有词义，表示某种感情和语气，不能单独作谓语，必须和动词原形一起构成谓语。2.情态动词主要有：can，could；may，might；must；ought to；need；dare；shall；will；should；would。3.有些情态动词有过去式，如：can could，maymight，willwould，dare dared，have tohad to 等。4.情态动词的四个特点：（1）情态动词不能单独做谓语。（2

2、）情态动词后接动词原形。（3）情态动词自身都有一定的词义。（4）情态动词在句中不受任何人称、数的影响（have to 除外）。基本用法1.can 与could 的基本用法1）表示能力，常译为“能，会”。can 表示现在的能力，could 表示过去的能力。I can play basketball now,but I couldnt when I was young.2）表示推测，可能性，常译为“可能”，常用于疑问句和否定句中；用于否 定句中，cant/couldnt 意为“不可能”；是有依据有把握的推测(可能性大)，could 的可能性比can小。Tom cant be in the clas

3、sroom.I saw him playing on the playground just now.3）表示请求或许可，常译为“可以”。could 比can 的语气更加委婉,回答时只用can.Can/could I use your phone?Yes,you can.No,you cant.4）表示理论上或习惯上的可能性，意为“可能会”,用于肯定的陈述句中。Anybody can make mistakes in his or her life.5）表示惊讶、怀疑，不相信等，常用于否定句 或疑问句中。How can he be late for the opening ceremony?2

4、.could have done 1）表示遗憾后悔，“本来可以做而实际上没做”2）表示对过去的肯定推测,”可能”They could have won the race,but they didnt try hard enough.If I had followed your advice,I could have succeeded.3.cant/couldnt have done 不可能做了某事（表示对过去的情况进行否定的推测）But for your advice,I couldnt have done it successfully.4.cant.too./cant.enough 再也

5、不过分，越。越好 You cant be too careful to cross the road.You cant be careful enough to cross the road.你过马路时越仔细越好。辨析填空（can/cant/could/couldnt）（1）I can speak English，but I speak Japanese.（2）She play several instruments at the age of eight.（3）Can/Could I use your studio?Of course you .（4）You park over there.

6、（6）It be quite cold at night here.（7）What he be doing at this time of night?（8）He have finished so much work in so short a time.（9）He have passed the exam，but he was too careless.开车的时候再小心也不过分。_cantcouldcancancancancant/couldntcouldYou cannot be too careful while driving a car.=You cant be careful en

7、ough while driving a car.5.can 与be able to 表示“能力”时的区别（1）can 一般指现在自身具有的能力，be able to表示经过努力后具有的能力。Babies can swim when they were born.(自身具有的能力)Without his hard work,he was not able to get good grades.(经过努力后)（2）can 只有现在式和过去式，而 be able to 有各种时态。（3）be able to do sth.的过去式 was/were able to do sth.可以表示在过去设法

8、做成了某事，相当于managed to do sth。At last,they were able to escape from the big fire.辨析填空（can/be able to）（10）Will you come?（11）The young man （not）carry the big box.（12）This time I failed the exam，but Ill pass the exam next time.（13）The fire was very big，but most people escape from it.be able tocantbe able

9、towere able to 二，may may 与might might 的用法1）表示请求或许可，常译成“可以”。用于一般疑问句;肯定回答用may/can;否定回答用 mustnt/cant.May I come in?Yes,you can/may.No,you may not/cant/mustnt.2）表示推测（把握不大），“可能”，多用于肯定句，might的可能性比may小。He may come,or he may not.3）表示祝愿，用于祈使句；May you succeed!祝你成功！4）may have done sth.可能做了某事 might have done st

10、h.可能做了某事（对过去事情的推测）/本来可能做了某事（虚拟语气）昨晚汤姆不在家。他可能去看电影了_ 你本来可以给他更多的帮助，尽管你很忙._Last night Tom wasnt at home.He might have gone to the cinema.You might/could have given him more help，though you were busy.三 must 与 have to 的用法1.must 的用法（1）表示命令或强烈的建议，“必须”，mustnt 表示“不准，禁止”。All students must obey the school rules

11、.用must问句时;肯定回答用must，否定回答用neednt/dont have to Must I be home before eight oclock?Yes,you must./No,you neednt.（2）表示说话人的一种态度，“偏要，非要”Why must he go out in the bad weather?（3）表示肯定推测，意为“一定，肯定”，可能性比can大，只能用于肯定句中。表推测时must 的否定形式是cant/couldnt(不可能)。Tom cant be in the classroom.I saw him playing on the playgrou

12、nd just now.对现在情况的肯定推测：must+动词原形;对过去情况的肯定推测：must+have done He must be ill.He looks vey pale and drawn(憔悴的).must 强调主观看法“必须”只有一种形式 否定形式mustnt 表示“禁止”have to强调客观需要“不得不”，有多种时态形式；否定形式dont have to 表示“不必”I must hurry up or Ill be late.He cant see things clearly.He has to wear glasses.You dont have to leave

13、so early.英译汉（1）You must be home by 11 oclock._（2）You mustnt smoke here._（3）Must we finish the work today?_ Yes，you must./No，you neednt/dont have to._（4）You mustnt tell others._ （5）You dont have to tell others._（6）They must be anxious to learn about local customs._ 你必须在 11 点之前回家。你不准在这里吸烟。我们今天必须完成这项工作

14、吗？是的，你们必须完成。/不，不必。你不准告诉别人。你不必告诉别人。他们一定急于了解当地的风俗习惯。（7）He is in high spirits.He must have received an award._（8）Why must you always interrupt me?_ 单句写作（9）昨晚你一定睡得很晚，因为你的眼睛通红。_（10）现在他一定在做他的作业。_他神采飞扬，一定是获奖了。你为什么非要总是打断我呢？You must have gone to bed late last night，for your eyes are red.He must be doing his

15、homework now.四 shallshall 与should should 的用法1.shall 的用法（1）用于第一、三人称的疑问句中，表示征求意见或请求指示。Shall he come in now?（2）用于第二、三人称的陈述句中，表示 命令、警告、允诺或威胁等。You shall be punishied for what you have done.（必须）（3）用于第三人称的陈述句，在条约、规 定、法令等文件中表示义务或规定，意为“应该”“必须”。Persons under 18 shall not be employed in night work.(不得)2.should

16、 的用法（1）表示义务、义务，劝告、建议、命令等，意为“应该”。We should be strict with ourselves.（2）表示有一定根据的推测，意为“可能，应该会”。If the train is on time,she should arrive in Beijing by seven oclock.（3）表示说话人的惊讶、愤怒、失望等特 殊情感，意为“竟然”。I am surprised that you should speak ill of me.(说某人坏话)should have done 表示“本该做某事（而实际上未做）”shouldnt have done 表

17、示“本不该做某事（而实际上做了）”You should have told me the truth.英译汉（1）Shall she go now?_（2）He shall do it by himself.（3）You shall have the book when I finish reading it._（4）You shall fail if you dont work harder._（5）He shall be punished sooner or later._（6）No reader shall remove a book from the library without p

18、ermission._她现在可以走了吗？（请求指示）他得自己做。（命令）这本书我读完就给你。（允诺）你如果不更加努力工作就会失败。(警告)他迟早要受到惩罚的。（威胁）未经许可，读者不准把书带出图书馆。（规定）（7）It should be a nice day tomorrow._（8）Its strange that he should believe the prediction._ 单句写作（9）你本应该请求帮助的。_（10）你本不该把这个消息告诉她。_明天应该是个好天气。（推测）真奇怪，他竟会相信这则预言。（惊讶）You should have asked for some help.

19、（劝告）You shouldnt have told her the news.（批评）五 ought to ought to 的用法ought to 是情态动词，没有人称、数和时态的变化，后接动词原形，用法与should 基本相同,”应该”。否定形式：ought not to do=oughtnt to do“不应该”（1）表责任和义务。表示按道理应该，指客观责任或义务，可用 should 代替，但比should语气重 I ought to help her because she is in trouble.（2）表劝告，建议或命令。和 should可换用，但疑问句中常用 should。y

20、ou ought to balance career and family.should I open the window?（3）表推测，和 should可换用 Mary ought to be here soon.（4）ought to have done sth.=should have done sth.过去本应该做某事（实际上没 有做）oughtnt to have done sth.=shouldnt have done sth.过去本不该做某事（实际上做了）（1）To be a top student，we （应该）be strict with ourselves in ever

21、ything we do.（2）Once lost in the forest，you （应该留在）where you are，waiting for help.（3）Ill tell Mary about her new job tomorrow.You （应该告诉）her last week.（4）He looks so upset；I （不应该告诉）him the bad news so early.ought toought to stayought to have toldought not to have told六 will will 与would would 的用法will 与

22、would 的用法（1）表示请求、建议，用于第二人称的疑问句中，would 比will 的语气更加委婉。Would you pass me the bottle?（2）表示意志、愿望或决心，意为“将、要”。will 指现在，would 指过去。I will never do that again.They said that they would accept the invitation.（3）表示一种习惯、倾向或固有性质等，意为“惯于，总是”。will 指现在，would 指过去。Oil will float on water.On summer evenings they would d

23、ance in the park.would 与used to（1）would表示过去的习惯性动作时，强调特定情况下的“倾向”；used to 着眼于过去和现在的对比，暗示现在不再是这样了 He would go to the park as soon as he was free.(特定情况：空闲)My father used to go to work by bike,but now he goes to work by car.（与现在形成对比）英译汉（1）Will you hand me that book?_（2）Would you please tell me something

24、about local customs?_（3）She said she would keep her word._（4）She would spend one hour dressing up before going out._ 她说她愿意履行她的诺言。（决心）请你告诉我一些当地的风俗好吗？（请求）请你把那本书递给我好吗？她总是打扮一个小时才出门。（习惯）辨析填空（will/would）（7）People die without air or water.（8）When we were children，we gather around Grandpa after supper，liste

25、ning to his stories.（9）you mind my smoking here?单句写作（10）He （总是）get up at eight when he was on the farm.（11）People （以前）think that the earth is flat.（12）The baby was born to a poor farmers family.Nobody knew he （成为）the 21st president of United States of America 40 years later.willwouldWouldwouldused t

26、owould become七 had better had better 最好had better+动词原形：最好。否定形式：had better not do 最好不要d better 是had better 的缩略形式（1）（我们最好留在）in the open when an earthquake happens.（2）Youd better （不要搬动家具）.We had better staynot move the furniture八 need need 需要（1）need 作为情态动词的特点：无时态、人称的变化，多用于否定句和疑问句。need do sth需要做某事，needn

27、t do sth 不必做某事。You neednt telephone him now.对need 引出的一般疑问句，肯定回答用must，否定回答用neednt.Need I finish the work today?Yes,you must./No,you neednt.（2）neednt have done sth.原本不必做某事（3）need作为实义动词，有人称，时态和数的变化，可以有以下搭配：need sth.需要某物 The homeless need our help.need to do sth.需要做某事 I need to finish the task on time.n

28、eed doing（=need to be done）需要被（主动形式表被动意义）My phone needs rapairing.=My phone needs to ne repaired.1）My room is a mess，but I （不必打扫）it before I go out tonight.2）Need I come?Yes，you （必须）./No，you （不必）.3）As you worked late yesterday，you （原本可以不必来）this morning.4）我的车需要洗了。_ neednt cleanmustneedntneednt have c

29、omeMy car needs washing./My car needs to be washed.九 dare dare 敢（1）dare 作为情态动词，没有人称和数的变化，后接动词原形,dare do sth 敢于做某事；否定：dare not do sth 不敢做某事；多用于条件句、疑问句和否定句中；No one dare go there.She dare not go out alone at night.（2）dare 作为实义动词，有人称，数和时态的变化，有如下搭配：dare(to)do sth.敢于做某事 She dared to swim across the river.dare sb.to do sth.激某人做某事，问某人有没有胆量做某事。单句写作（1）我不敢独自一人去冬泳。_ （2）你怎么敢说那样的话？_（3）无人敢提及此事。_I dare not go winter swimming alone.How dare you say that?No one dare speak of it.1.Finish your writing after class.2.Surf the Internet for more information about the related knowledge after school.