• 教學科研
    【皖樅高中學?!扛咧杏⒄Z情態動詞精講與解析
    來源: 發布時間:2015-04-05

    概  說

    助動詞(auxiliary)主要有兩類:基本助動詞(primary auxiliary)和情態助動詞(modal auxiliary)?;局鷦釉~有三個:do, have和be;情態助動詞有十三個:may, might; can, could; will, would; shall, should; must, need, dare, used to, ought to. 上述兩類助動詞的共同特征是,在協助主動詞構成限定動詞詞組時,具有作用詞的功能:
    1) 構成否定式:
    He didn't go and neither did she.
    The meeting might not start until 5 o'clock.
    2) 構成疑問式或附加疑問式:
    Must you leave right now?
    You have been learning French for 5 years, haven't you?
    3) 構成修辭倒裝:
    Nowhere can he obtain any information about his sister.
    Hardly had he arrived when she started complaining.
    4) 代替限定動詞詞組:
    A: Who can solve this crossword puzzle?
    B: Tom can.
    A: Shall I write to him?
    B: Yes, do.
    情態助動詞的特征
    基本助動詞與情態助動詞最主要的區別之一是,基本助動詞本身沒有詞義,而情態助動詞則有自己的詞義,能表示說話人對有關動作或狀態的看法,或表示主觀設想:
    What have you been doing since? (構成完成進行體,本身無詞義)
    I am afraid I must be going. (一定要)
    You may have read some account of the matter. (或許已經)
    除此之外,情態助動詞還有如下詞法和句法特征:
    1) 除ought和used以外,其他情態動詞后面只能接不帶to的不定式。如果我們把ought to和used to看做是固定詞組的話,那么,所有情態動詞無一例外地只能接不帶to的不定式:
    We used to grow beautiful roses.
    I asked if he would come and repair my television set.
    2) 情態助動詞在限定動詞詞組總總是位居第一:
    They need not have been punished so severely.
    3) 情態助動詞用于第三人稱單數現在時的時候,沒有詞形變化,即其詞尾無-s形式:
    She dare not say what she thinks.
    4) 情態動詞沒有非限定形式,即沒有不定式、-ing分詞和-ed分詞形式:
    Still, she needn't have run away.
    5) 情態助動詞的“時”的形式并不是時間區別的主要標志。在不少場合,情態助動詞的現在時和過去時形式都可以表示現在、過去或將來時間:
    Would you mind very much if I ask you to do something?
    She told him he ought not to have done it.
    6) 情態助動詞之間是相互排斥的,即在一個限定動詞詞組中只能出現一個情態助動詞,但有時卻可以與have和be基本助動詞連用:
    You should have washed the wound.
    Well, you shouldn't be reading a novel.
    現將情態助動詞的各種形式列表如下:
    情態助動詞的意義和用法
    情態助動詞從最普通的意義上來說,是修飾分句意義的一種方式,它可以反映說話者對其表述是否真實和可能的程度作出判斷。但不同的情態助動詞本身所包含的意義和用法又不同,下面逐個分析。
    1) can和could的用法
    1. 表示能力或客觀可能性,還可以表示請求和允許。如:
    Can you finish this work tonight?
    Man cannot live without air.
    — Can I go now?   — Yes, you can.
    注意:①could也可表示請求,預期委婉,主要用于疑問句,不可用于肯定句,答語應用can(即could不能用于現在時態的簡略答語中)。如:
       Could I come to see you tomorrow?
       Yes, you can. (否定答語可用No, I'm afraid not.)
    ②can表示能力時,還可用be able to代替。如:
       I'll not be able to come this afternoon.
    2. 表示驚異、懷疑、不相信的態度。(主要用在否定句、疑問句或驚嘆句中)
    Can this be true?
    How can you be so careless!
    This cannot be done by him.
    3. “can(could) + have + 過去分詞”的疑問或否定形式表示對過去發生的行為懷疑或不肯定。如:
    He cannot have been to that town.
    Can he have got the book?
    2) may和might的用法
    1. 表示許可。
    表示請求、允許時,might比many的語氣更委婉一些,否定回答時要用mustn't表示“不可以”、“禁止”、“阻止”之意。如:
    You may drive the car.
    — Might I use your pen?   — No, you mustn't.
    用May I ... 征詢對方許可在文體上比較正式,在口氣上比較客氣。在日??谡Z中,用Can I ... 征詢對方意見在現代口語中更為常見。
    2. 用于祈使句中表示祝愿。如:
    May you succeed!
    3. 表示推測、可能(疑問句不能用于此意)。
    He may be very busy now.
    4. “may(might) + have + 過去分詞”表示對過去發生的行為的推測。如:
    He may not have finished the work.
    3) must和have to的用法
    1. 表示必須、必要。如:
    You must come in time.
    回答must引出的問句時,如果是否定的回答,不能用mustn't,而要用needn't或don't have to。
    — Must we hand in our exercise books today?
    — Yes, you must. (No, you don’t have to.)
    2. “must be + 表語”的結構表示推測,它的否定或疑問式用can代替must。
       This must be your pen.
    3. “must + have + 過去分詞”的結構常用在肯定句中,表示對過去發生的行為的推測。它的否定或疑問式用can代替must。
    He must have been to Shanghai.
    4. have to的含義與must相似,兩者往往可以互換使用,但have to有各種形式,隨have的變化而定。must與have to有下列幾點不同:
    ① must表示的是說話人的主觀看法,而have to則往往強調客觀需要。如:
    The play is not interesting. I really must go now.
    I had to work when I was your age.
    ② must一般只表現在,have則有更多的時態形式。
    ③ 二者的否定意義不大相同。如:
    You mustn't go. 你可不要去。
    You don't have to go. 你不必去。
    ④ 詢問對方的意愿時應用must。如:
    Must I clean all the room?
    4) dare和need的用法
    1. need表示“需要”或“必須”,作情態動詞時,僅用于否定句或疑問句中,在肯定句中一般用must, have to, ought to,或should代替。如:
    You needn’t come so early.
    — Need I finish the work today?
    — Yes, you must.
    注意:needn't + 不定式的完成式“表示本來不必做某事而實際上做了某事”。如:
    You needn't have waited for me.
    2. Dare作情態動詞時,主要用于疑問句、否定句和條件從句中,一般不用在肯定句中。如:
    How dare you say I'm unfair.
    He daren't speak English before such a crowd, dare he?
    3. Dare和need常用作實義動詞,有時態、人稱和數的變化,所不同的是,作實義動詞時,在肯定句中,dare后面通常接帶to的不定式,在否定和疑問句中,dare后面可接帶to或不帶to的不定式。如:
    I dare to swim across this river.
    He does not dare (to) answer.
    Don't you dare (to) touch it!
    I wondered he dare (to) say that.
    He needs to finish it this evening.
    5) shall和should的用法
    1. Shall用于第一人稱,表示征求對方的意愿。如:
    What shall we do this evening?
    2. Shall用于第一、第三人稱疑問句中,表示說話人征求對方的意見或向對方請示。如:
    Shall we begin our lesson?
    When shall he be able to leave the hospital?
    3. Shall用于第二、第三人稱,表示說話人給對方命令、警告、允諾或威脅。如:
    You shall fail if you don't work harder. (警告)
    He shall have the book when I finish reading. (允諾)
    He shall be punished. (威脅)
    4. Should表示勸告、建議、命令,其同義詞是ought to;在疑問句中,通常用should代替ought to。如:
    You should go to class right away.
    Should I open the window?
    Should的含義較多,用法較活,現介紹三種其特殊用法。請看下面的句子:
    ① I should think it would be better to try it again. 我倒是認為最好再試一試。
    ② You are mistaken, I should say. 依我看,你是搞錯了。
    ③ I should advise you not to do that. 我倒是勸你別這樣做。
    ④ This is something I should have liked to ask you. 這是我本來想問你的。
    從以上例句可以看出:情態動詞should用于第一人稱時可以表示說話人的一種謙遜、客氣、委婉的語氣。
    Should還可以用在if引導的條件從句,表示一件事聽起來可能性很小,但也不是完全沒有可能。相當于“萬一”的意思。從句謂語由should加動詞原形構成,主句謂語卻不一定用虛擬語氣。如:
    ⑤ Ask her to ring me up if you should see her. 你萬一見到她,請讓她給我打個電話。
    ⑥ If you should change your mind, please let us know. 萬一你改變主意,請通知我們。
    ⑦ Should I (If I should) be free tomorrow I will come. 萬一我明天有時間,我就來。
    此外,Why(or How) + should結構表示說話人對某事不能理解,感到意外、驚異等意思。意為“竟會”。如:
    ⑧ Why should you be so late today? 你幾天怎么來得這么晚?
    ⑨ — Where is Betty living? — 貝蒂住在哪里?
    — How should I know? — 我怎么會知道呢?
    ⑩ I don't know why you should think that I did it. 我真不知道你憑什么認為這件事是我干的。
    5. “should + have + 過去分詞”結構一般表示義務,表示應該做到而實際上沒有做到,并包含一種埋怨、責備的口氣。如:
    She should have finished it.
    I should have helped her, but I never could.
    You should have started earlier.
    6) will和would的用法
    1. 表示請求、建議等,would比will委婉客氣。如:
    Would you pass me the book?
    2. 表示意志、愿望和決心。如:
    I will never do that again.
    They asked if we would do that again.
    3. 用“will be”和“will(would) + have + 過去分詞”的結構表示推測,主要用于第二、三人稱。前者表示對目前情況的推測,后者表示對已經完成的動作或事態的推測。如:
    This will be the book you want.
    He will have arrived by now.
    The guests would have arrived by that time.
    I thought you would have finished this by now.
    4. Would可表示過去反復發生的動作或某中傾向。Would表過去習慣時比used to正式,并沒有“現已無此習慣”的含義。如:
    The wound would not heal.
    During the vacation he would visit me every week.
    5. 表料想或猜想。如:
    It would be about ten when he left home.
    What would she be doing there?
    I thought he would have told you all about it.
    7) ought to的用法
    1. Ought to表示應該。如:
    You ought to take care of him.
    2. 表示推測。注意與must表示推測時的區別:
    He must be at home by now. (斷定他已到家)
    He ought to be home by now. (不十分肯定)
    This is where the oil must be. (比較直率)
    This is where the oil ought to be. (比較含蓄)
    3. “ought to + have + 過去分詞”表示過去應做某事而實際未做。如:
    You ought to have asked him (but you didn't).
    這時,ought to和should可以互相換用。
    注意:在美國英語中,ought to用于否定句和疑問句時,to可以省略。如:
    Ought you smoke so much?
    You oughtn't smoke so much.
    8) used to,had better,would rather的用法
    1. Used to表示過去的習慣動作或狀態,現在已不存在,在間接引語中,其形式可不變。如:
    He told us he used to play football when he was young.
    在疑問句、否定句、否定疑問句或強調句中,可有兩種形式:
    疑問句 
    Did you use to go to the same school as your brother?
    Used you to go to the same school as your brother?
    否定句
    I usedn't to go there.
    I didn't use to go there.
    Usedn't 亦可拼作usen't,但發音皆為[ju:znt]。
    否定疑問句 
    Usen't you to be interested in the theatre?
     Didn't you use to be interested in the theatre?
    強調句 
    I certainly used to smoke, but it was a long time ago.
     I certainly did use to smoke, but it was a long time ago.
    其反意疑問句或簡略回答中,也有兩種形式:
    She used to be very fat, didn't she? (正式)/ use(d)n't she? (口語)
    Did you use to play chess? Yes, I did.
    Used you to get up early in the morning? Yes, I did. (Yes, I used to.)
    2. Had better意為“最好”,后接不帶to的不定式。如:
    — We had better go now.
    — Yes, we had (we'd better / we had better).
    Hadn't we better stop now? (Had we better not stop now?)
    I think I'd better be going. (用于進行時態,表“最好立即”)
    You had better have done that. (用于完成時態,表未完成動作)
    注:①had best與had better同意,但較少用。②You had better … 用于同輩或小輩,對長輩不可用。
    3. Would rather意為“寧愿”,表選擇,后接不帶to的不定式。如:
    I'd rather not say anything.
    Would you rather work on a farm?
    — Wouldn't you rather stay here?
    — No, I would not. I'd rather go there.
    由于would rather表選擇,因而后可接than。如:
    I would rather work on a farm than in a factory.
    I would rather watch TV than go to see the film.
    I would rather lose a dozen cherry trees than that you should tell me one lie.
    I'd rather you didn't talk about this to anyone. (句中的'd rather不是情態動詞,would在此是表愿望的實義動詞)
     
         高中情態動詞的重難點突破
     一.概念:
       情態動詞是表示能力,義務,必須,猜測等說話人的語氣或情態的動詞.
    二.相關知識點精講:
    1.can
    1)表能力
    can表能力時意味著憑體力或腦力或技術等可以無甚阻力地去做某事。
    I can climb this pole. 我能爬這根桿子。
    He is only four , but he can read. 他只有4歲,但已認得字了。
    Fire can’t destroy gold. 火燒不毀金子。
    因為can不能和其他助動詞連用,所以表示將來式時用will be able to
    You will be able to skate after you have practiced it two or three times.
    你練習兩三次后就會溜冰了。
    2)表可能性
    多用于否定與疑問結構中,但也可用在肯定句中。
    Can the news be true? 這消息可能是真的嗎?
    It can’t be true. 它不可能是真的。
    What can he possibly mean? 他可能是什么意思?
    can 用在肯定句中表示理論上的可能性(一時的可能)。
    A horse in the center of London can cost a lot of money.
    Attending the ball can be very exciting.
    The road can be blocked. 這條路可能會不通的。
    may 在肯定句中表示現實的可能性。
    The road may be blocked. 這條路可能不通了。
    3)表示允許(和may意思相近)常見于口語。
    Can (May) I come in ? 我能進來嗎?
    Can I smoke here ? 我可以在這里抽煙嗎?
    2.could的用法
    1)表過去的可能和許可,(多用于間接引語中)
    At that time we thought the story could not be true.
    那時我們認為所說的事不可能是真的。
    Father said I could swim in the river.
    爸爸說我可以在河里游泳。
    2)表過去的能力
    I could swim when I was only six.
    我剛六歲就能游泳。
    Could在肯定句中表示過去的能力時,常表抽象的一般的能力。
    He could be very naughty when he was a child.
    他小時候會是很頑皮的。
    3)表“允許”??杀硎疚窨蜌獾奶岢鰡栴}或陳述看法
    Could I use your bike?
    Yes, you can.
    他會記得那時嗎?
    I’m afraid I couldn’t give you an answer today.
    恐怕我今天不能回答你。
    The teacher said you could go to the store for sweets.
    老師說你可以去商店買糖。
    4)Could/can+have done 結構表示對過去發生的事情的“懷疑”或“不肯定”。 could 加完成式還用于肯定句時一般表過去可能完成而卻未完成的動作。
    Can they have won the basketball match?
    他們贏了那場籃球賽嗎?
    What you referred to just now can have made her very sad.
    你剛剛所談到的可能令他很傷心。
    You could have completed the task a little earlier.
    你本來能早點完成任務的。(但事實上并沒有提前完成任務)
    I could have passed my examination easily but I made too many stupid mistakes.
    我本可以輕易通過考試,但我犯了太多不該犯的錯誤。
    如表具體做某一件事的能力時,則須用 be able to .
    He was able to translate the article without a dictionary.
    他可以不用詞典翻譯那篇文章。
    Can表示一貫的能力 ,be able to表示客觀能力和通過努力可以達到的能力
    I can’t swim. But I am sure I will be able to swim through more practicing.
    The fire spread through the hotel, but everyone was able to get out
    When the boat sank he was able to swim to the bank
    3.may 的用法
    1)表示請求、可以、允許。
    You may drive the tractor. 你可以開那臺拖拉機。
    2)當回答由may 引起的問題時,否定答語要用must not,表示“不許可”、“不應該”、“不行”。
    May I come in?
    Yes, you may.
    No,you can’t
    No, you may not .
    No ,you mustn’t
    No ,you’d better not.
    3) may /might 推測性用法 可能
    He may be right.
    He may not come today  (可能不)
    He may /might come tomorrow.
    注意 :  (1)只用于肯定和否定句中,不用于疑問句中。
     (2) might 比may可能性更小
       He might get a job.
       He may get a job.
     (3) may no 可能不  can not不可能
      He may not come
       He can’t come
    3)表建議(可和as well 連用)
    You may(might)as well stay where you are.
    你還是原地待著好。(may as well 有“還是……的好”的含義)
    4)表祝愿
    May you be happy!
    might
    1)表過去的“可能”和“允許”多用于間接引語。
    She said that he might take her dictionary.
    她說他可以拿她的詞典去用。
    除在間接引語中外,might一般不表示過去的“可能”與“許可”。表過去的“可能”可用could,表過去的“許可”可用were (was) allowed to。
    2)表現在的“可能”,其可能性要比may小。
    Electric irons could be dangerous; they might give you a severe shock.
    電熨斗會有危險,它可能電著人。
    3)may (might) + have +done 表示對過去發生行為的推測,含有“想必”、“也許是”的意思。
    It may have been true. 這事也許是真的。
    He might not have settled the question. 他可能尚未解決那個問題。
    4.must 的主要用法。
    1)表示必須、必要
    We must do everything step by step .我們必須按部就班地做一切事情。
    Why must you always bother me? 為什么你偏要打擾我呢。
    2)must be + 表語的結構,通常表示猜測,含有“一定”之意。(只用在肯定句中)
    He must be an honest boy. 他一定是個誠實的男孩。
    This must be your room. 這一定是你的房間。
    3)must 的否定式有兩個:當回答由must引起的問題時,否定答復要用needn’t或don’t have to 表示“不必”、“無須”、“用不著”、“不一定”的意義。當表示“不應該”、“不許可”、“禁止”時,就用must not。
    Must I go tomorrow?明天我必須去嗎?
    Yes, please.是的,請吧!
    No , you needn’t. 不,你不必去。
    4)must +have +過去分詞的結構,常用在肯定句中,表示對過去發生行為的推測,含有“一定”、“準是”的意思。否定和疑問句用can。
    She must have studied English before.她以前一定學過英語。
    5.have to的含義與must是很接近的,只是have to 比較強調客觀需要,must著重說明主觀看法。
    I must clean the room.(主觀想法)
    I have to clean the room.(客觀需要)
    另外,have to 能用于更多時態:
    We had to be there at ten .我們得在十點鐘到那里。
    We will have to reconsider the whole thing.
    這一切我們將不得不重新加以考慮。
    have to 的否定式:don’t have to do 表示“不必做……”之意。
    6.ought to 的用法
    Ought to 后接動詞原形,表義務,但不及must 那樣具有信心,如:
    You don’t look well. You ought to go to see the doctor.
    你氣色不好,應該去看病。
    Ought to 用于否定句,其否定形式可縮略為oughtn’t ,如:
    You oughtn’t to smoke so much. 你不應該抽這么多煙。
    也可以用于疑問句,如:
    Ought you to smoke so much?你應該抽這樣多煙嗎?
    Ought to 在間接引語中表過去時形式不變,如:
    He said you ought to tell the police.
    他說你應該去報告警察。
    7.shall的用法
    1)用于第一人稱征求對方的意見,如:
    What shall I wear on the journey? 我路上穿什么好呢?
    Shall we dance? 我們跳舞好嗎?
    2)shall 用于第二、三人稱時表允諾,警告,命令,威脅(現已少見),如:
    She shall get her share. 她可以得到她的一份。
    You shall have it back tomorrow.你明天可以將它拿回。
    情態動詞should一般不應被認為是情態動詞shall的過去式,主要用法有:
    1)用于第一人稱疑問句中詢問對方的意愿,但語氣較委婉溫和,如:
    What should we do now? 我們現在該怎么辦?
    2)表示應該、必須,常與must 換用。例如:
    We should (must) master a foreign language at least.
    我們應當至少掌握一門外語。
    3)“should+be+表語”的結構,表示推測或驚奇。例如:
    They should be back by now. 他們現在應該回來了吧。
    I am sorry that she should be so careless. 我感到遺憾她竟會那樣粗心。
    4)“should+have+過去分詞”的結構,表示過去該做而實際上尚未做的動作或行為;其否定則表示發生了不應該發生的行為。其同義結構“ought to have +過去分詞”,表示過去“早應該”、“本當”之意,語氣較強。例如:
    I should have thought of that. 這一點我是應當想到的。(但沒想到)
    They should not have left so soon.他們不應當走得這么早。(但已走了)
    5) 在“It is natural (strange, natural, necessary, surprised, impossible, important ) that……”句型中,主語從句中的謂語動詞要用should +動詞原形”表示“理所當然”、“奇怪”、“必要”、“驚異”等的意思。在lest(以免)、for fear (that) (以防)、in case(以備萬一)等之后也要用should+動詞原形;在advise, sugest, order, demand, request 等的從句中should+do”例如:
    It is necessary that he(should) be sent there at once.
     有必要馬上派他到那里去。
    It is strange that he should say so. 他會說這樣的話真是奇怪。
    Let us go at once lest we should be late for the train.
     我們馬上走吧,以免趕不上火車。
     
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