Unit 6 ElectricityOxford EnglishModule 3 Natural elements GrammarModal verbs情態(tài)動詞情態(tài)動詞may(might)can(could)needought toshall(should)must(Modal verbs)本身有一定的詞義本身有一定的詞義,表示語氣的單詞。但表示語氣的單詞。但是是不能獨立作謂語不能獨立作謂語,只能和動詞原形一起只能和動詞原形一起構(gòu)成謂語構(gòu)成謂語.情態(tài)情態(tài)動詞用在行為動詞前動詞用在行為動詞前,表示說話人對這一動作或狀態(tài)的表示說話人對這一動作或狀態(tài)的看法或主觀設(shè)想看法或主觀設(shè)想.情態(tài)動詞will(would)dare情態(tài)動詞情態(tài)動詞沒有人稱和數(shù)的變化沒有人稱和數(shù)的變化。情態(tài)動詞情態(tài)動詞不能單獨作謂語動詞不能單獨作謂語動詞，只能與，只能與動詞動詞原形一起原形一起做謂語，沒有人稱和數(shù)的變化。做謂語，沒有人稱和數(shù)的變化。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 shall/should will/would need have to能能夠夠可能可能必必須須應(yīng)該應(yīng)該意愿意愿需要需要不得不不得不+動詞動詞原形原形情態(tài)動詞表示說話人對某一動作或狀態(tài)的態(tài)度，可表示情態(tài)動詞表示說話人對某一動作或狀態(tài)的態(tài)度，可表示“可能可能”、“可以可以”、“需要需要”、“必須必須”或或“應(yīng)當(dāng)應(yīng)當(dāng)”等之意。等之意?？隙隙?否定否定 縮寫否定縮寫否定 can can not cant couldcould not couldnt maymay not /mightmight not mightnt must must not mustnt shouldshould not shouldnt needneed notneedntYes,you may.He may be Tom.在表示請求許可時，can，could沒有時態(tài)區(qū)別，只是could在語氣上更加委婉客氣。speak two languages.You mustnt talk loudly in public.No,it cant be her.No,I cant.You may not/cannot play in the kitchen.肯定會”，只用于肯定句。must/must notYou mustnt climb this ladder.Benny:Yes,I can.表示推測，意為“可能”，常用于否定句和疑問句中，此時cant譯為“不可能”。can/cantmay/may notmust/must not本課重點情態(tài)動詞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 able 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的用法的用法用法總結(jié)用法總結(jié):1.can表示表示_.2.can 后面動詞用后面動詞用_.3.can的否定形式是：的否定形式是：_或或_.4.一般疑問句是將一般疑問句是將can_.有能力做某事有能力做某事原形原形cantcannot提前提前 can and cannot2.表示推測，意為表示推測，意為“可能可能”，常用于否定句和疑問句中，常用于否定句和疑問句中，此時此時cant譯為譯為“不可能不可能”。Can it be Mary?會是瑪麗嗎？會是瑪麗嗎？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。她去上海出差了。can/could的其他用法的其他用法：1.could用來表示請求許可時，語氣委婉，主要用于疑用來表示請求許可時，語氣委婉，主要用于疑問句，不能用于肯定句，答語應(yīng)用問句，不能用于肯定句，答語應(yīng)用can（即：（即：could不不能用于現(xiàn)在時態(tài)的簡略答語中）。能用于現(xiàn)在時態(tài)的簡略答語中）。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的過去式，意為的過去式，意為“能；會能；會”，表示過，表示過去的能力。去的能力。He could play the piano when he was 5.當(dāng)他當(dāng)他5歲時，他就會彈鋼琴了。歲時，他就會彈鋼琴了。2.在表示請求許可時，在表示請求許可時，can，could沒有時態(tài)區(qū)別，沒有時態(tài)區(qū)別，只是只是could在語氣上更加委婉客氣。在語氣上更加委婉客氣。Could I use your dictionary?我可以用你的字典我可以用你的字典嗎？嗎？Yes,you can.可以?？梢?。注意：注意：Hi and Lo are talking about themselves.What are they saying?Read their 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 may/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(許可).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的用法的用法觀察：觀察：總結(jié)：總結(jié)：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.請求請求允許允許原形原形cant/cannotmay notYou _(You _(可以可以可以可以)leave)leave now.否定句：否定句：否定句：否定句：一般疑問句：一般疑問句：一般疑問句：一般疑問句：肯定回答：肯定回答：肯定回答：肯定回答：否定回答：否定回答：否定回答：否定回答：就劃線部分提問：就劃線部分提問：就劃線部分提問：就劃線部分提問：mayYou may not leave now.May I leave now?Yes,you may.No,you may not.When may I leave?2.may的過去式為的過去式為might，表示推測時兩者無時態(tài)區(qū)別，表示推測時兩者無時態(tài)區(qū)別，不過不過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還可還可表示推測，談?wù)摽赡苄?，意為表示推測，談?wù)摽赡苄?，意為“可能；或可能；或許許”，一般用于肯定句中。，一般用于肯定句中。It may rain tomorrow.明天可能會下雨。明天可能會下雨。注意：注意：may&mightmay&might3.表示希望、祈求、祝愿時，表示希望、祈求、祝愿時，may常譯為常譯為“祝愿祝愿”，通常結(jié)構(gòu)為，通常結(jié)構(gòu)為“may+主主+v.”。May you have a good time！祝你玩得開心！祝你玩得開心！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._ 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 the 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We use must and must 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的用法的用法觀察：觀察：總結(jié)：總結(jié)：1.must表示表示_和和_.后接后接_2.Must 提問，肯定回答：仍用提問，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 Li 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