2020年北师大版高中英语选修7课件：Unit21 Grammar—Conditionals and Mixed Conditionals & Modality

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1、,Unit 21 Human Biology,PART 1,语法导学,PART 2,达标检测,GrammarConditionals and Mixed Conditionals & Modality,PART 1,语法导学,感悟规律 重点难点剖析,感知以下课文原句，完成方框下的小题,(一),1.在if虚拟条件句中，如果表示与现在事实相反的假设，则if条件句的谓语动词的时态为： ，主句的谓语动词的形式为：_ ，如 。 2.在if虚拟条件句中，如果表示与过去事实相反的假设，则if条件句的谓语动词的形式为： ，主句的谓语动词的形式： 。如 。 3.如果虚拟条件句和主句表示的动作发生的时间不一致，则

2、主从句动词的形式应根据各自所表示的时间进行调整。这种结构称为：错综虚拟条件句。如 。,查看答案,过去式,would/should/could/might,动词原形,句4, 句5,had 过去分词,would/should/,could/mighthave 过去分词,句1, 句3,句2,(二),1.In the summer of 1996，everything must have been going perfectly for the twenty-five-year-old Texan cyclist. 2.He had been offered contracts by big spor

3、ting companies，such as Nike，and did not need to worry about money. 3.He should have gone earlier，but he had ignored the pain so that he could continue racing. 4.When he went to the doctor that day，he could not have known what was about to happen to him. 5.There was a 40% chance he would survive and

4、a 60% chance he might die.,6.During periods when he did not have to have chemotherapy，he rode his bike 30 to 50 miles a day. 7.Many people doubted Armstrongs ability to become a top cyclist again but they need not have worried. 8.However，we must not forget that he is different from other stars. 9.Mo

5、ney and success do not seem to interest him and he must have a different kind of motivation. 10.But young，strong men must realise that this can happen to them，too.,4.must have done sth. 表示对过去事情的肯定判断，如 ；must not do sth. 意为：千万不要做某事，如 ；mustdo表示对现在事情的肯定判断，如 ；还表示“必须做某事”，如 。 5.should have done sth. 表示“本该做

6、某事但没做”，如 。 6.could do sth. 表示“能够做某事”如 ；couldnt have done sth. 表示“过去不可能做某事”，如 。 7.might do表示“或许”，如 。 8.have to的否定式为：dont/didnt have to, 表示“不必”， 如 。,查看答案,句1,句8,句9,句10,句3,句3,句4,句5,句6,9.need既可用作情态动词，也可用作实义动词。如在句2中用作 动词；在句7中用作 动词。neednt have done sth. 表示“过去本不需要做某事而做了”。,查看答案,实义,情态,一、条件句和混合条件句 在英语中，我们一般把条件

7、句分为两种，即真实条件句和非真实条件句。非真实条件句亦可称为虚拟条件句。虚拟语气表示说话人的愿望、假设、猜测或建议，而不表示客观存在的事实。 1.if虚拟条件句,If I were a bird，I could fly. 如果我是一只鸟的话，我就能飞了。 If we had started earlier，we would not have missed the train. 如果我们早点出发，就不会错过这班火车了。 If he shouldnt come tomorrow，we would put off the meeting till next Monday. 要是他明天来不了，我们将把

8、会议推迟到下周一。 注意：在if虚拟条件句中，如果从句谓语动词有were/should/had时，可以省略if，然后把were/should/had提到主语前面，形成部分倒装。,Were I at school again，I would study harder. 如果我可以再上一次学，我会更努力地学习。 Had you come earlier，you would have caught the bus. 如果你早一点儿到，你就会赶上那趟公交车了。 Should it rain tomorrow，we would not go climbing. 如果明天下雨，我们就不去爬山。,2.混合条

9、件句 通常情况下，虚拟条件句和主句表示的动作发生的时间是一致的，但不一致时主从句动词的形式应根据各自所表示的时间进行调整。我们把这种结构称为混合虚拟条件句或错综虚拟条件句。可将其分为两种： (1)想象中的现在状态可能对过去有影响； If I were you，I would have taken his advice. 如果我是你的话，我就接纳他的意见了。 (2)想象的过去事件可能对现在有影响； If I had taken my raincoat with me this morning，I would not be wet now. 如果今天早上带上雨衣的话，我现在就不会淋湿了。,3.含蓄

10、虚拟条件句 有时虚拟的条件并不是直接通过条件句来表示，而是用一些词或短语或上下文暗示来说明，我们称之为含蓄虚拟条件句。 (1)用介词(短语)表条件，如：but for，without： But for your advice，I couldnt have done it so successfully. 要是没有你的建议，我就不会做得那么成功。 (2)用连词(but，or)，副词(otherwise)表条件： I would have attended the party，but I was too busy. 要不是我太忙，我就去参加那个聚会了。,(3)分词短语暗示条件： Having kn

11、own in time，we might have prevented the accident. 要是及时得知的话，我们也许能阻止这场事故。 Given more attention，the tree could have grown better. 如果多留心的话，这棵树本来可以长得更好。 (4)通过上下文表条件： I would have come to see you that day.Unfortunately，it was raining so hard. 我本来打算那天来看你的，不巧的是那天下大雨。,二、情态动词 1.概述 情态动词表示说话人的语气和情态，如需要、可能、意愿和怀疑

12、等。情态动词有一定的词义，但不完整，必须和主要动词的原形一起构成谓语，常用的情态动词有：can，could，may，might，must，ought to，need，dare以及shall，should，will，would；下列短语也表达情态动词的意义：be able to，had better，have to，used to。,2.情态动词的用法,3.常见情态动词的用法 (1)can 表能力。 He can speak English.他会讲英语。 表客观条件允许做某事。 I can call you tomorrow.我明天可以给你打电话。 表推测(多用于疑问句和否定句)。 That c

13、ant be Maryshes in hospital. 那不可能是玛丽她在住院。,(2)could 表过去的能力。 I could drive a car before I left school. 毕业前我就会开车了。 表可能性(既可表示过去的可能性，也可表示现在的可能性，比can的程度要弱)。 He said the news could be true. 他说这消息可能是真的。,用于委婉、客气地提出请求、想法、问题或陈述看法，回答时用原形。 Could I use your dictionary? Yes，you can. 我能用一下你的词典吗？ 行，可以。 (3)may 表征求对方的

14、意见。 May I sit here？我可以坐这儿吗？ 表允许 You may come if you wish. 如果你想来，你就来。,表可能性。 We may meet her at the station. 我们可能会在车站遇到她。 表祝愿。 May you succeed！祝你成功！ (4)might 表可以做的事或可能发生的事，might比may的口气委婉或表示实现的可能性更小些。 Thinking it might rain，I decided to go by car. 我想可能会下雨，所以决定开车去。,may (just) as well，might as well，意为“不妨

15、”，用于提出建议。 You might as well have a try.你不妨试一下。 表可能性。 We might finish the task ahead of time. 我们可能会提前完成这项任务。 (5)must 表必须做的事，着重主观看法。其否定式mustnt表示禁止。对其问句作否定回答时不用mustnt，而用neednt或dont have to。have to强调客观需要。 I must go now.现在我必须走了。 Must I go to work? No，you neednt./Yes，you must. 我必须去上班吗？ 不，你不必去。/是的，你必须去。,表推

16、测，只用于肯定句，意为“一定”，常指有根据、有把握地推测。 There must be nobody.那儿肯定没人。 “偏要，偏偏”(指做令人不愉快的事)。 Must you shout so loudly? 你非得喊这么大声吗？ Why must it rain on Sunday? 为什么偏偏在星期天下雨？,(6)shall 用于主语为第二、三人称的陈述句中，表示说话人给对方的命令、允诺、警告、强制、威胁、决心等。 You shall apologize to him.你要向他道歉。 用于主语为第一、三人称的疑问句，表示征求对方的意见和指示。 Shall I fetch some wate

17、r for you? 要我去给你拿些水吗？ 用于主语为第三人称的陈述句中，表示条约、规定、法令等中的义务，常译为“应，必须”。 Members of the club shall pay for registration. 该俱乐部成员应付注册费。,(7)should/ought to 表推测，表示说话者进行尝试性的判断，常译为“按道理说应该”。 With her talent and experience，she should do well by herself. 凭着她的才能和经验，她自己应该能做得很好。 should可以表示说话者惊奇、怀疑、不满、失望、愤怒等情绪。 He should

18、 be careless to such an important matter. 他竟然对这么重要的事粗心。 should/ought to表“应该”，多表示责任、义务、道德、法律等方面。 Every citizen should/ought to obey the law. 每个公民都应该遵守法律。,(8)will 表意愿、意志、决心。 I will succeed.我会成功的。 表示倾向或习惯性动作。 Fish will die out of water. 离开水，鱼会死的。 用于疑问句表示请求、邀请。 Will you see a movie with me? 你愿意和我去看电影吗？,

19、(9)would 表过去的意志、愿望和决心。 I felt he would go with me.我感觉他愿意和我去。 委婉地提出请求、建议，比will更委婉，肯定回答用will。 Would you join us？你愿意加入我们吗？ 表过去习惯性的动作。 As a young man，he would play basketball. 他年轻的时候常常打篮球。,(10)need常用于疑问句和否定句中，否定式为neednt。 Need I heat the dish? No，you neednt. 我需要热一下菜吗？ 不，不必。 (11)dare多用于疑问句、否定句和条件句中。 Whats

20、 the matterdarent you read what it says? 怎么了你难道不敢把上面写的念出来吗？ If you ever dare call me that name again，youll be sorry. 你胆敢再那样叫我，你会后悔的。,4.“情态动词have done”的用法 could have done sth. 可能做了某事(一般用于否定句和疑问句)；过去本来可以做某事(实际上并没有做) may/might have done sth. 可能做了某事 neednt have done sth. 本不必做某事(实际上做了) cant have done sth

21、. 不可能做了某事 must have done sth. 一定做了某事 should/ought to have done sth. 本该做某事但实际上未做 shouldnt/ought not to have done sth. 过去不该做某事但做了 He couldnt have gone abroad.I saw him just now. 他不可能出国了。我刚才还看见他了。,I neednt have got up so early. 我本来不必那么早起床的。,.用所给动词的正确形式或适当的情态动词填空 1.The workers were not better organized，

22、otherwise they _ (accomplish) the task in half the time.(2019天津) 2.What a pity！You missed the sightseeing，or we _(have) a good time together.(2019江苏) 3.In todays information age，the loss of data cause serious problems for a company.(2018北京) 4.They might have found a better hotel if they _(drive) a f

23、ew more kilometers.(2018北京),查看答案,would have,accomplished,would have had,can,had driven,5.I cant find my purse.I (leave) it in the supermarket yesterday，but Im not sure.(2018天津) 6.If we (catch) the flight yesterday，we would be enjoying our holiday on the beach now.(2018天津) 7.Its strange that he _(tak

24、e) the books without the owners permission.(2018江苏) 8.If the new safety system (put) to use，the accident would never have happened.(2017北京) 9.My room is a mess，but I clean it before I go out tonight.I can do it in the morning.(2017天津),查看答案,could/might have left,had caught,should have taken,had been

25、put,neednt,10. (be) it not for the support of the teachers，the student could not overcome her difficulty.(2017江苏),查看答案,Were,.单句改错(每小题仅有1处错误),1.We can chose between staying at home and taking a trip. (2016全国) 2.Some classmates suggest we can go to places of interest nearby. (2016全国) 或Some classmates

26、suggest we can go to places of interest nearby. 3.If you are me，would you talk to them？(2015四川),查看答案,choose,should,were,5.I knew that they will be worried about me because I was so far away，and that my mother would not sleep if she knew.(2012浙江) 6.Meanwhile，I found out that with more patience I must

27、 make my toys last. (2012新课标全国),查看答案,would,could/might,4.We must found ways to protect our environment.(2015全国),find,PART 2,达标检测,当堂检测 基础达标演练,1.I didnt see your sister at the meeting.If she (come)，she would have met my brother. 2.If I hadnt had your help，I _(not，finish) the work ahead of time. 3.If h

28、e (take) his doctors advice，he might still be alive. 4.If he (come) here，he would tell us about it. 5.Had I turned off the electric heater，the house (not，catch) fire. 6.But for the meeting，I (go) home at the time.,.单句语法填空,查看答案,had come,wouldnt have finished,had taken,were to come/came/should come,wo

29、uldnt have caught,would have gone,7.Tom，you are too lazy.The work (finish) yesterday. 8.I love the weekend，because I (not，get) up early on Saturdays and Sundays. 9.I have lost one of my gloves.I (drop) it somewhere. 10.If she (not，lose) her precious belongings，she could have lost something far more

30、importanther life!,查看答案,should have been finished,neednt get,must have dropped,hadnt lost,11.Tom comes from Australia and he speak English very well. 12.I heard you bought a new book. I have a look? 13.It is sunny today；we take an umbrella. 14. you like to have dinner with me? 15. we finish the comp

31、osition in class? No，you neednt. 16.May I smoke here? No，you . 17.He is so strong that I fight against him.,.用适当的情态动词填空,查看答案,can,May,neednt,Would,Must,mustnt/cant,dare not,18.We have received the letter yesterday，but it didnt arrive. 19.He swim when he was ten years old. 20. you have a good time!,查看

32、答案,ought to/should,could/was able to,May,21.If I am in your position，I would marry her. 22.If he have taken my advice，he would have succeeded in the competition. 23.If it rained last night，the ground would be wet now. 24.Its surprising that Mary would love such a person as Jack. 25.If he was free to

33、day，we would send him to Beijing. 26.The law says that drivers cant drive after drinking.,.单句改错(每小题仅有1处错误),查看答案,were,had, had,should,were,mustnt,27.Dare you to tell your parents about your school records? 28.A few years ago I might afford to bring my wife to this place for dinner. 29.If you may go，at least wait until the storm is over. 30.She told him he ought not do it.,查看答案,could,must, to,