1、情態(tài)動詞,東平實驗中學(xué)王鵬,1. must,1) 表示必須、必要。是說話人的主觀看法 You must come in time. 在回答引出的問句時，如果是否定的， 不能用mustnt（禁止，不準(zhǔn)），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) 表示推測、可能性（只用于肯定的陳述句） 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,表示請求和允許。might比 may語氣更委婉，而不是過去式 否定回答時可用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.？征徇對方許可時比較正式

3、和客氣， 而用 Can I.？在口語中更常見。,2) 表示推測、可能性（不用于疑問句）。,might不是過去式，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（體力、知識、技能）。 Can you lift this heavy box?（體力） Mary can speak three languages.（知識） Can you skate?（技能）,可用be able to代替。 Can只有一般現(xiàn)在時和一般過去式

4、；而be able to則有更多的時態(tài)。 Ill not be able to come this afternoon.,2) 表示請求和允許。,-Can I go now? - Yes, you can. / No, you cant. 此時可與may互換。在疑問句中還可用could, might代替，不是過去式，只是語氣更委婉，不能用于肯定句和答語中。 - Could I come to see you tomorrow? - Yes, you can. ( No, Im afraid not. ),3) 表推測可能性。,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. 否定句和疑問句中，只能用can表猜測可能性。 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“應(yīng)該”，常用來表示勸告、建議；認(rèn)為“某人應(yīng)該做某事”或“有義務(wù)責(zé)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. 這時它可以和 ought to， be supposed to 互換使用,2) Should (ought to)表示推測時，是指有一定根據(jù)的推測，意為“可能、該”,-When can I come for the photos? I need them tomorrow, -They _ be ready by 12:00,七。need,1need作情態(tài)動詞無人稱或數(shù)的變化，后接動詞原形，多用于否定句和疑問句中。 如：Youneedntwo

7、rry.你不必?fù)?dān)心,2由need引出的一般疑問句，肯定回答常用must或haveto;否定答語常用neednt.如：,NeedIanswerthequestion?我需要回答那個問題嗎？ Yes,youmust. -Yes,youhaveto.是的，你必須回答。 -No,youneednt./you dont have to不，不必了。,由must引出的一般疑問句，肯定回答用must,否定答語用neednt或donthaveto。如：,MustIdotheworknow?我必須現(xiàn)在干這個活嗎？ Yes,youmust/haveto. -No,youneednt/donthaveto.,注意點一

8、：,表推測可能性：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、表推測的用法,1. must have done過去肯定做了某事 Since the road is wet, it must have rained last night. 不存在 mustnt have done 的形式。其否定或疑問形式須用 can(could) 來表示. 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. 我找不到我的鑰匙了。我可能昨天把他們落在學(xué)校了。 John may/might not have passed the exam; he looks very sad.約翰可能沒有通過考試。他看起來很憂傷。,3.can/could have done 表推測一般用在否定句和疑問句中，表示不相信或懷疑的