高中英语 Unit 2 Healthy eating Period 3 Grammar课件 新人教版必修3.ppt

情态动词的用法,语法,1、重温情态动词的语法特征。 2、掌握情态动词ought to, ought not to, have to, dont have to, mustnt , neednt. 3、懂得区分should 和ought to , 区分neednt 和mustnt 。,情态动词是高考的必考知识点，看似简单，但准确运用就没那么容易了。所以讲授情态动词时，就是要把那些似是而非的内容搞清楚。 在必修三第一单元，已经把情态动词的语法特征讲述了一遍。本单元是必修三第二单元。首先重温第一单元的情态动词的语法特征，再进一步通过should 引出ought to ,并区分它们用法上的不同。然后又通过must引出have to,也把它们用法上的不同区分开来。接着，学习否定形式：ought not to, dont have to, mustnt , neednt .并区分mustnt和neednt的用法。 最后，通过练习来巩固所学的知识。,情态动词的语法特征： 1. 情态动词有一定的意义，表示或暗示某种情绪或态度，表示可能、建议、愿望、必要、允许、能力等。但只表示期待或估计某事的发生，不能表示正在发生或已经发生的事情。 2. 情态动词不能独立使用，必须和实义动词一起构成谓语。 3. 情态动词没有人称和数的变化，即不随主语的不同而变化。 4. 有些情态动词, 如can、will也有一般式和过去式的变化。但情态动词的“时态”形式并不是时间区别的主要标志。不少情况下, 情态动词的现在式形式和过去式形式都可用来表示现在时间、过去时间和将来时间。,知识点回顾：,1. _ it be Li Ping who broke the glass? No. It _ be Wu Dong who did it. A. Can; must B. Must; need C. May; must D. Need; can 2. Dont forget to visit me when you come to Beijing. _. A. I dont B. I wont C. I cant D. I havent 3. Could I use your bike? Yes, surely you _. A. might B. will C. can D. should 4. Her brother _ be at home now, because he was seen playing basketball in the stadium just now. A. mustnt B. neednt C. cant D. shouldnt 5. When can you get my car repaired? I need it tomorrow morning. It _ be ready by 8:00. A. can B. need C. might D. should,温故而知新（一）,6. Are you coming for dinner? Im not quite sure. I _ go to my uncles instead. A. must B. would C. should D. might 7. Dont believe him. What he said _ be true. A. mustnt B. neednt C. shouldnt D. may not 8. _ I go home now, sir? No, you _. You should finish the composition first. A. Might; wouldnt B. May; had better not C. Must; mustnt D. Need; mustnt 9. _ he use your bike? Certainly. Here is the key. A. Shall B. Must C. Will D. Does 10. Mr Bush is on time for everything. How _he be late for the important meeting? A. would B. should C. might D. need,温故而知新（二）,1、你应该做适当的运动。You should do some sports. 2、你应该慢慢地进食，这样有助于消化。 You should eat slowly and its good for digestion. 3、你应该保持房间的整洁。You should keep your room clean。,should / ought to“应该”(一）,should常表示劝告、建议、命令，与ought to意义相近，但ought to多表示责任、义务，语气强烈。反映客观情况或涉及法律义务和规定时一般用 ought to。 例如： Young people should learn how to use computers. （建议） Every citizen ought to obey the law. （义务） 试比较： 你应该慢慢地进食，这样有助于消化。 You should eat slowly and its good for digestion. 你（胃不好），应该慢慢地进食，这样才能消化得好。 You ought to eat slowly and its good for digestion. 你应该帮忙布置饭桌。（能帮就帮） You should help to set the dinner table。 （我忙得团团转，或者客人太多）你应该帮忙布置饭桌。 You ought to help to set the dinner table.,should / ought to“应该”（二）,1.You _go to the class right now. 2.They _ come tomorrow. 3.He thought that they _ take part in the design. 4._we to do it at once? 5.According to the law, you _ help him get a good education as you are his father.,巩固练习(should /ought to),should /ought to,ought to,ought to,Ought,ought to,must 用来表示“命令”、“推测”等含义。 1）表示规定、指令 You must have a passport if you want to go abroad. 如果你想出国，你必须有护照。 2）表示猜测，语气非常肯定，近乎确定的意味 You must be ill. I can see it from your face. 你一定是病了，我能够从你的脸色看出来。 3) 表示“必须” -Must I hand in the exercise today?-Yes, you must. 我今天必须交这个练习吗？是的，必须。 I dont like this TV set. We must buy a new one. 我不喜欢这台电视机。我们必须买一台新的。,must / have to“必须”(一）,表示“必须”这个意思时，must 和have to 稍有区别。must着重说明主观看法，have to 强调客观需要，意思是“不得不”。另外，have to 能用于更多时态。 There was no more bus. They had to walk home. 再也没公共汽车了，他们不得不走路回家。 I am afraid You will have to wait a while.我看你得等一会儿。 At every step I had to pull my legs out of the snow. 我每走一步都得将双腿从雪中拔出来。 注意have to在疑问句中的位置。如： Do you have to go out today? 你今天一定得出去吗? Does he have to finish the work tomorrow? 他明天非做完这项工作不可吗?,must / have to“必须”（二）,1. If you _ go, at least wait until the rain stops. A. can B. must C. should D. would 2. My parents never remember my telephone number, and they always _look it up. A. must B. can C. should D. have to 3. _ it be Li Ping who broke the glass? No. It _ be Wu Dong who did it. A. Could ; may B. Can; can C. May; must D. Can; must 4. I missed the bus, so I _ go home on foot. A. must B. may C. can D. had to,巩固练习(must/have to),1. must的否定形式must not / mustnt ，“不能，不许”。语气比较强烈,表示禁止,不许可。 You mustnt come here without permission. 未经允许，你不能来这儿。 We mustnt waste our time. 我们不能浪费时间。 Passengers must not walk across the railway line. 禁止旅客横穿铁路。 You mustnt miss that modern ballet，It is extremely good. 你可不要错过这个现代芭蕾舞剧，它好极了。 One must not divorce oneself from the masses. 不能脱离群众。,否定形式（一）,2. 说“不必“须用need not / neednt 。由must引起的疑问句，肯定回答要用must或have to, 否定回答要用neednt或dont have to, 意思是“不必” 。 Must I finish the task right now? 我现在必须完成这个工作吗？ Yes, you must. / Yes, you have to. 是的。 (No, you neednt. / No, you dont have to. 不，不必。) -Must we hand in our exercises today? -No，You neednt. -我们必须今天交练习吗? -不，不必今天交。 注意:didnt need to则常表示过去未做也勿须做的动作。这时候的need是实义动词。 I didnt need to take a taxi； it is only five minutes walk to the station. 到车站只须走五分钟，我不需要坐出租汽车。,否定形式（二）,3. have to 的否定形式是dont have to, 相当于neednt。请注意时态。 They dont have to buy a computer at present. 他们目前没有必要买电脑。 Mr. Johnson doesnt have to work very hard to earn a living. 约翰逊先生不必为了谋生拼命干活。 We will not have to get up very early tomorrow. 我们明天不必起得很早。 I shall not have to go to the clinic today for a little cough. 我今天不必为一点点咳嗽就去诊疗所。 注意didnt have to常表示过去未做也勿须做的动作。如： I didnt have to interpret it for her，for she knows Chinese. 我勿须为她翻译，她懂汉语。 You didnt have to leave the party early last night. 昨晚你不必早点离开晚会。,否定形式（三）,4. ought的否定形式由直接加not构成: ought not to / oughtnt to You ought not to follow me as I am wrong. 因为我错了，你不应该听我的。 The reference book ought not to be in the reading-room. 这本参考书不该在阅览室里。 It ought not to be so hot today.Its so strange! 今天不该这么热。很怪! He ought not to be so obstinate. 他不该这样固执。 You oughtnt to smoke so much. 你不应当抽烟太多。 You ought not to have been so rude.你不该这样粗鲁。 You ought not to have taken his skates without asking him. 你不该没有得到他的许可就把他的冰鞋拿走。,否定形式（四）,1. Johnny, you _play with the knife, you _hurt yourself. A. wont ; cant B. mustnt ; may C. shouldnt ; must D. cant ; wouldnt 2. The boss has given everyone a special holiday, so we _ go to work tomorrow. A. cant B. mustnt C. neednt D. shouldnt 3. What do you think we can do for our aged parents? You _ do anything except to be with them and be yourself. A. dont have to B. oughtnt to C. mustnt D. cant 4. You _ follow me if I am wrong. A. must B. dont have to C. wouldnt D. ought to 5. Its raining outside, so you _go . A. cant B. mustnt C. neednt D.ought not to,巩固练习(情态动词的否定形式),一、should / ought to“应该”: should常表示劝告、建议、命令，与ought to意义相近。 但ought to多表示责任、义务，语气强烈。反映客观情况或涉及法律义务和规定时一般用 ought to。 二、must / have to“必须”: must 用来表示“命令”、“推测”等含义。 must 表示“必须”这个意思时，must 和have to 稍有区别。must着重说明主观看法，have to 强调客观需要，意思是“不得不”。 另外，have to 能用于更多时态。注意have to在疑问句中的位置。,三、否定形式: 1.must的否定形式must not / mustnt ，“不能，不许”。语气比较强烈,表示禁止,不许可。 2.说“不必“须用need not / neednt 。由must引起的疑问句，肯定回答要用must或have to, 否定回答要用neednt或dont have to, 意思是“不必” 。注意:didnt need to则常表示过去未做也勿须做的动作。这时候的need是实义动词。 3. have to 的否定形式是dont have to, 相当于neednt。请注意时态。注意didnt have to也表示过去未做也勿须做的动作。 4.ought的否定形式由直接加not构成: ought not to或oughtnt to,你每天最少要练习一小时口语。 2. 我每天不得不练习一小时口语！ 3. 你应该每天练习不止一小时。 4. 你应该读一下这个。它写得很好。 5. 你必须读这个。写得精彩极了！,You must practise speaking English at least an hour a day