初中英语情态动词课件jg

1、情态动词,东平实验中学王鹏,1. must,1) 表示必须、必要。是说话人的主观看法 You must come in time. 在回答引出的问句时，如果是否定的， 不能用mustnt（禁止，不准），而用neednt, dont have to（不必）. - Must we hand in our exercise books today? - Yes, you must. - No, you dont have to / you neednt.,1. must,2) 表示推测、可能性（只用于肯定的陈述句） 1 Youre Toms good friend, so you must know

2、 what he likes best. 2 Your mother must be waiting for you now.,Might and may,表示请求和允许。might比 may语气更委婉，而不是过去式 否定回答时可用cant 或mustnt，表示“不可以，禁止”。 -Might/ May I smoke in this room? - No, you mustnt. - May/Might I take this book out of the room? - Yes, you can. (No, you cant / mustnt. ) 用May I.？征徇对方许可时比较正式

3、和客气， 而用 Can I.？在口语中更常见。,2) 表示推测、可能性（不用于疑问句）。,might不是过去式，它所表示的可能性比may小。 1He may /might be very busy now. 2Your mother may /might not know the truth.,三、can, could,1) 表示能力（体力、知识、技能）。 Can you lift this heavy box?（体力） Mary can speak three languages.（知识） Can you skate?（技能）,可用be able to代替。 Can只有一般现在时和一般过去式

4、；而be able to则有更多的时态。 Ill not be able to come this afternoon.,2) 表示请求和允许。,-Can I go now? - Yes, you can. / No, you cant. 此时可与may互换。在疑问句中还可用could, might代替，不是过去式，只是语气更委婉，不能用于肯定句和答语中。 - Could I come to see you tomorrow? - Yes, you can. ( No, Im afraid not. ),3) 表推测可能性。,肯定句中：can, may表示可能性； In Dongping, s

5、ometimes it can be really cold. Tom may go camping with us tomorrow, but he is not sure. 否定句和疑问句中，只能用can表猜测可能性。 Someone is knocking at the door, and who can it be? It cant be Tom because he has gone to Beijing.,五. should,表示“应该”，常用来表示劝告、建议；认为“某人应该做某事”或“有义务责任做某事”。 We should obey traffic laws. You shou

6、ldnt watch TV every day。 You shouldnt have made this kind of silly mistakes. 这时它可以和 ought to， be supposed to 互换使用,2) Should (ought to)表示推测时，是指有一定根据的推测，意为“可能、该”,-When can I come for the photos? I need them tomorrow, -They _ be ready by 12:00,七。need,1need作情态动词无人称或数的变化，后接动词原形，多用于否定句和疑问句中。 如：Youneedntwo

7、rry.你不必担心,2由need引出的一般疑问句，肯定回答常用must或haveto;否定答语常用neednt.如：,NeedIanswerthequestion?我需要回答那个问题吗？ Yes,youmust. -Yes,youhaveto.是的，你必须回答。 -No,youneednt./you dont have to不，不必了。,由must引出的一般疑问句，肯定回答用must,否定答语用neednt或donthaveto。如：,MustIdotheworknow?我必须现在干这个活吗？ Yes,youmust/haveto. -No,youneednt/donthaveto.,注意点一

8、：,表推测可能性：must, can, may, might, cant, couldnt -I heard they went skiing in the mountains last winter. - it _ true because there was little snow where.,二、表推测的用法,1. must have done过去肯定做了某事 Since the road is wet, it must have rained last night. 不存在 mustnt have done 的形式。其否定或疑问形式须用 can(could) 来表示. 例如： He

9、cant have missed the way. I drew him a map. “The dictionary has disappeared. Who could have taken it?”,may / might have done,I cant find my keys. I may / might have left them at the school yesterday. 我找不到我的钥匙了。我可能昨天把他们落在学校了。 John may/might not have passed the exam; he looks very sad.约翰可能没有通过考试。他看起来很忧伤。,3.can/could have done 表推测一般用在否定句和疑问句中，表示不相信或怀疑的