1、 Unit 6 ElectricityOxford EnglishModule 3 Natural elements GrammarModal verbs情态动词情态动词Do you know “Modal verb”?Warming-upmay (might)can (could)needought toshall (should)must( Modal verbs)本身有一定的词义本身有一定的词义,表示语气的单词。表示语气的单词。但是但是不能独立作谓语不能独立作谓语,只能和动词原形一起只能和动词原形一起构成构成谓语谓语.情态动词用在行为动词前情态动词用在行为动词前,表示说话人对这表示说话人
2、对这一动作或状态的看法或主观设想一动作或状态的看法或主观设想.情态动词will(would)dare情态动词情态动词没有人称和数的变化没有人称和数的变化。 情态动词情态动词不能单独作谓语动词不能单独作谓语动词，只能与，只能与动词原形一起动词原形一起做谓语，没有人称和数的做谓语，没有人称和数的变化。变化。A bird can fly .Fish cant live without water.You must hand in your homework at once. You mustnt talk loudly in public. can/could may/might must shal
3、l/should will/would need have to能够能够可能可能必须必须应该应该意愿意愿需要需要不得不不得不+ 动词原形动词原形情态动词表示说话人对某一动作或状态的态度，可表示情态动词表示说话人对某一动作或状态的态度，可表示“可能可能”、“可以可以”、“需要需要”、“必须必须”或或“应当应当”等之意。等之意。 肯定肯定 否定否定 缩写否定缩写否定 can can not cant couldcould not couldnt maymay not / mightmight not mightnt must must not mustnt shouldshould not sho
4、uldnt needneed notneedntcan/cantmay/may notmust/must not本课重点情态动词He can play football and speak two languages.But he cant cook or play chess. can的用法的用法and 肯定句；肯定句；or否定句否定句I can dance well. Can you?No, I cant. ButI can swim well.Can you?can的用法的用法We use can and cannot(cant) to say we are able or not ab
5、le to do things.We can use electricity to do many things.We cannot(cant)electricity.Can you think of an example?Yes, I can./ No, I cannot(cant).can的用法的用法用法总结用法总结: 1.can表示表示_. 2.can 后面动词用后面动词用_. 3. can的否定形式是：的否定形式是：_或或_. 4. 一般疑问句是将一般疑问句是将can_.有能力做某事有能力做某事原形原形cantcannot提前提前 can and cannot canMy elder
6、brother cannot/cant drive a car.Can your elder brother drive a car?Yes, he can.No, he cant.What can your elder brother do?2.表示推测，意为表示推测，意为“可能可能”，常用于否定句和疑问，常用于否定句和疑问句中，此时句中，此时cant译为译为“不可能不可能”。Can it be Mary? 会是玛丽吗？会是玛丽吗？No, it cant be her. She has gone to Shanghai on business. 不可能是她。她去上海出差了。不可能是她。她去上
7、海出差了。can/could的其他用法的其他用法：1.could用来表示请求许可时，语气委婉，主要用于用来表示请求许可时，语气委婉，主要用于疑问句，不能用于肯定句，答语应用疑问句，不能用于肯定句，答语应用can（即：（即：could不能用于现在时态的简略答语中）。不能用于现在时态的简略答语中）。如：如：-Could I use your dictionary?-Yes, you can.(否定回答可用：否定回答可用：No, Im afraid not.或者是或者是you cant)could&cancould&can1.could是是can的过去式，意为的过去式，意为“能；会能；会”，表示过，
8、表示过去的能力。去的能力。He could play the piano when he was 5. 当他当他5岁时，他就会弹钢琴了。岁时，他就会弹钢琴了。2.在表示请求许可时，在表示请求许可时，can，could没有时态区别，没有时态区别，只是只是could在语气上更加委婉客气。在语气上更加委婉客气。Could I use your dictionary? 我可以用你的字典我可以用你的字典吗？吗？Yes, you can. 可以。可以。注意：注意：Hi and Lo are talking about themselves. What are they saying? Read their
9、 conversation and then complete the statements below with Can or Cannot. 1. Hi _ play football.2. Lo _ paint.3. Hi _ speak as many languages as Lo.4. Both Hi and Lo _ dance.5. Lo _ drive a car, but he _ play chess.6. Hi _ swim, but he _ play the guitar.cancancancancannotcannotcannotcannotYes, you ma
10、y/can.May/Can I sit down?may的用法的用法_I come in?Yes,you may/can.No, you may not /cant.May/Canmay的用法的用法We use may and may not to ask for and Give permission(许可). We also use can and cannot (cant) for the same purpose. May/Can I use you mobile phone?Yes, you may/can. No,you may not/cant.may的用法的用法 观察：观察：
11、总结：总结： 1：can/may表示：表示：_和和_.后接后接:_ 2: can的否定形式的否定形式:_ may 的否定形式：的否定形式：_May/Can I use your mobile phone？Yes, you may/can. No, you may not/cant.You may/can turn on the TV.You may not/cannot play in the kitchen. 请求请求允许允许原形原形cant/cannotmay not mayYou may not leave now.May I leave now?Yes, you may.No, you
12、 may not.When may I leave?2.may的过去式为的过去式为might，表示推测时两者无时态，表示推测时两者无时态区别，不过区别，不过might的可能性低于的可能性低于may。He might be sick.他可能是生病了。他可能是生病了。1.may还可还可表示推测，谈论可能性，意为表示推测，谈论可能性，意为“可能；可能；或许或许”，一般用于肯定句中。，一般用于肯定句中。It may rain tomorrow. 明天可能会下雨。明天可能会下雨。注意：注意：may&mightmay&might3.表示希望、祈求、祝愿时，表示希望、祈求、祝愿时，may常译为常译为“祝祝愿
13、愿”，通常结构为，通常结构为“may+主主+v.”。May you have a good time！祝你玩得开心！祝你玩得开心！ Daisy is not feeling well today. Benny is at home with her. Read their conversation below. Fill the blanks with may or can. Benny: Yes. I _. _ I carry your bag for you?Daisy: Yes, you may. Thats so kind of you, Benny. Imready to go. _
14、 you open the door for me?Benny: Yes, I can.Daisy: Thanks. MaycanCanBenny: How are you feeling, Daisy?Daisy: Not very well.Benny: _ I get you a chair?Daisy: Yes, thanks.Benny: Im going out. _ I borrow your bicycle, Daisy?Daisy: Yes, you may. Before you go to meet your friends, can you come and see t
15、he doctor with me?MayMay/CanWhat do these signs mean?You mustnt smoke here.You mustnt climb this ladder.You mustnt swim here.You mustnt use your mobile phone here.must的用法的用法Must you do homework now?Yes, I must. Must you do your homework?No, I neednt.must的用法的用法No, I dont have to.We use must and must
16、not (mustnt) to tell people what to do or what not to do. You must not/mustnt do that Benny!We must always be careful with electricity.They must not/mustnt play near the heater.must的用法的用法 观察：观察： 总结：总结： 1. must表示表示_和和_.后接后接_ 2. Must 提问，肯定回答：仍用提问，肯定回答：仍用_回答回答 否定回答：用否定回答：用_或或_1.We must listen to Miss L
17、i carefully.2. You must not/ mustnt be late for class.3. Must I clean the blackboard now? Yes, you must. No, you neednt. No, you dont have to.命令命令禁止禁止原形原形must you needntyou dont have to mustLily mustnt go to the library.Must Lily go to the library?Yes, she must.No, she neednt./doesnt have to.Where m
18、ust Lily go?1.must意为意为“必须；一定必须；一定”。must的否定形式的否定形式mustnt 意为意为“一定不要；千万别一定不要；千万别”或或“禁止；不禁止；不许许”。You mustnt make noise in the library. 你一定不要在图书馆吵闹。你一定不要在图书馆吵闹。注意：注意：must&mustntmust&mustnt2.must表示很有把握的推测，意为表示很有把握的推测，意为“一定会；一定会；肯定会肯定会”，只用于肯定句。，只用于肯定句。He won the prize in the English competition. His Englis
19、h must be very good.他在英语竞赛中获奖了。他英语一定很好。他在英语竞赛中获奖了。他英语一定很好。Daisy saw a doctor. The doctor told her what to do and what not to do. Help her write down the doctors instructions. drink more water go to bed early eat cold food share cups with others go out alone take the medicine on time1.I must drink mo
20、re water.2._3._4.I must not _5._6._I must go to bed early.I must take the medicine on time.eat cold food.I must not go out alone.I must not share cups with others. 观察：观察： 1. He may be Tom. Because he looks as tall as Tom. But I am not sure. 2. -Can the story be true? -It cant be true. He lied. 3. He
21、 must be at home. Look! The lights are on. 总结：总结： 1.can/may/must还可以用来表示还可以用来表示_. 2.可能性由大到小的排序：可能性由大到小的排序：_. 3. must表示一定，其表示一定，其“不可能不可能”是：是：_ 4. 表示可能时，表示可能时，_不用于肯定句。不用于肯定句。推测推测 must-may/can cant can 注意：注意：may&can&mustmay&can&must的双面性的双面性情态动词两要点情态动词两要点动词动词原形原形跟后面跟后面说话语气较委婉说话语气较委婉can能力能力may许可许可must责任或义
22、务责任或义务否定回答否定回答neednt换换should应该应该,would愿愿have to 被迫表被迫表客观客观.【记忆口诀记忆口诀】 （2016福州）福州）-Look at the young lady in redIs it MrsKing？-No，It _ be herShe is wearing a white dress today Acan Bmay Cmust Dcant（2016绵阳）绵阳）-Is Mr Brown driving here？-Im not sureHe _ come by trainAmay Bshall Cneed Dmust（2016滨州）滨州）-Must I go to law school and be a lawyer like you，Dad？-No，you _，sonYoure free to make your own decisionAcant Bmustnt Cshouldnt Dneednt
