高中英语Unit2HealthyeatingSectionⅢGrammar—情态动词（Ⅱ）学案（含解析）新人教版必修3.docx

Unit 2 Healthy eatingSection III Grammar情态动词（II）OK悟法YUFAJINGXI思维导图表示责任或义务(oughtto的用法表示劝告、建议或命令情态动词nhave to的用法表示推测情态动词用法 实义动词用法情态动词+have doneI语法精讲一、ought to的用法(1)表示责任和义务，意为“应该"，与should同义，但语气比should重，侧重于 “责任、义务、道德、法律”等方面。To be a popular student, we ought to be strict with ourselves.为了成为一名受欢迎的学生，我们应该对自己要求严格。名师点津ought to的否定形式为ought not to (oughtn，t to)； 一般疑问句是将 ought提至句首，其否定答语通常用doesn，t/don，t have to或needn't。一Ought he to see the doctor?他该去看医生吗？一Yes, he ought to. /No, he doesn，t have to.是的，他该去。/不，他不必去。You ought not to make this kind of mistake again.你不应该再犯这种错误了。(2)表示可能性，一般指较大的可能性，意为“按道理应该”。If he started at six, he ought to be here now.要是他6点就出发的话，这会儿该到这里了。二、need的用法1 .作情态动词(Dneed作情态动词时，常用于疑问句、否定句或条件句中，意为“需要”。一Need I finish the work today?一Yes, you must. /No, you needn，t.我需要今天干完这活吗？是的，必须干完。/不用，你不必干完。（2）needn t意为“不必”，表示客观上不必如此。There's plenty of time. You needn，t drive so fast.时间很充足，你不必开这么快。2 .作实义动词need作实义动词时，后可接名词、动名词、不定式等，有人称、时态和数的变化。The bike needs repairing.= The bike needs to be repaired.这辆自行车需要修理。三、have to的用法（Dhave to表示客观上的必要性，意为“不得不”。由于它是由“have + to”构成， 因此它有多种时态变化形式以及人称和数的变化，其疑问句和否定句由助动词do构成。It's too late. I have to go home now.天色太晚了，我现在得回家了。Did you have to leave now?你现在必须得走吗？We don，t have to go to school on Sundays.星期天我们用不着上学。（2）have to的否定式don，t have to,表示没有义务或没有必要做某事，意为“不必”， 常可以回答以must开头的疑问句。而must的否定式mustn't表示"禁止，不许”。You don't have to finish the work now.你现在没有必要完成这项工作。一Must we hand in our homework this afternoon?我们必须今天下午交家庭作业吗？一No, you don't have to/you needn，t.不，你们不必。（肯定回答为：Yes, you must.）（3）have to表示客观需要，而must则表示主观的看法。You must obey the rules of your school.你必须遵守学校的规章制度。I have to go now because it's getting dark.天快黑了，我必须得走了。四、情态动词+have done“情态动词+ have done”表示对过去事情的推测。各个情态动词的具体用法如下表：can/could have done1 .过去可能（表推测）2 .本能做而未做（表虚拟）should/ought to have done本该做而未做may/might have doneL过去也许做了（表推测）2.本可能做而未做（表虚拟）must have done一定已经做了needn，t have done本不必做而做了From what you said, she must have told you all about it. 从你所说的来看，她一定把一切都告诉你了。You should have told me earlier or I might have gone with them. 你应该早点告诉我，不然的话我就会和他们一块儿去了。They could have sent up the satellite successfully. 他们本来可以成功发射这颗卫星的。You ought to/should have been more careful.你本应该更小心一些的。You needn，t have told them about it.你本来没有必要告诉他们那件事。能课后财KEHOUXUNLIANI .选词填空（可变换形式）1. You mustn't go there alone; it's too dangerous. （mustn，t/needn，t）2. The park is so beautiful, so we shouldn't throw away rubbish everywhere. （shouldn，t/can，t）3. . You oughtn' t to have spent so much time playing computer games. （mustn，t/oughtn，t to）4. 一Shall I leave the room so that you two can talk?一No, you needn" t. （mustn，t/needn，t）5. They ough;to win for they，ve trained hard enough, （ought to/must）6. They had to stay in the office last night because of the snowstorm, （have to/must）7. 一Must I finish my work today?No, you needn，t. （need/must）8. As an athlete, he has to know his strengths and weaknesses, （have to/need）9. He finished all the work himself; in fact, he could have asked his friends for help, （need/could）10. Something bad must have happened if Mr Brown didn't turn up on time to have class as he always did. （have to/must）11. 补全句子1. I have just found that to attend an important classmeeting（我必须参加一个重要的班会）that afternoon.2. George can' t have gone too far（不可能走太远）.His coffee is still warm.3. I love the weekend, because I needn' t get up early（不必早起）on Saturdays and Sundays.4. The length of the article shouldbe limited j;o00 words or so（应当限制 在400词左右）.5. The last important thing you should remember（你应当记住的）is that you haveto send the article to me before June 28.6. I badly need someone to help n）e with my oral English（需要有人来帮助我学 英语口语），at which lots of Chinese students are bad.7. You needn't havejeferred to it （本不必提起'它），for I had known about it.8. You must have seen（肯定看过）the film The Pursuit of Happiness.9. Mr Smith can' t have gone to Beijing（不可能去北京了），for I saw him in the library just now.10. You oughtn，t to/shouldn，t have written （本不应该写）so fast.