情態(tài)動詞相關(guān)知識

1、參見：必修三UNIT1、2情態(tài)動詞中還做助動詞有：will, would , shall , should實義動詞：need , dare一、情態(tài)動詞是一種本身有一定的詞義，表示說話人的情緒，態(tài)度或語氣的動詞， 但不能單獨作謂語，只能和其他動詞原形構(gòu)成謂語。We can be there on time tomorrow.我們明天能按時去那兒。May I have your name? 我能知道你的名字嗎？Shall we begin now? 我們現(xiàn)在就開始嗎？You must obey the school rules.你必須遵守校規(guī)。二、情態(tài)動詞數(shù)量不多，但用途廣泛,主要有下列：can

2、(could), may (might), must, n eed, / ought to, dare (dared), shall (should), will (would) .,has to /have/had to, had better情態(tài)動詞的位置：情態(tài)動詞在句中放在謂語動詞之前，謂語動詞前若有助動詞，則在助動詞之前，疑 問句中，情態(tài)動詞則在主語之前。I can see you. Come here. 我能看見你，過來吧。He must have bee n away. 他一定走了。What ca n I do for you? 你要什么？How dare you treat us

3、 like that ！ 你怎能那樣對待我們！三、情態(tài)動詞的特點：一般情況下，情態(tài)動詞無人稱和數(shù)的變化，(has to,have to;shall第一人稱)情態(tài) 動詞后面跟的動詞需用原形，否定式構(gòu)成是在情態(tài)動詞后面加 "not"。個別情態(tài) 動詞有現(xiàn)在式和過去式兩種形式，過去式用來表達更加客氣，委婉的語氣，時態(tài) 性不強，可用于過去，現(xiàn)在或?qū)?。He could be here soon. 他很快就來。We can't carry the heavy box.我們搬不動那箱子。rm sorry I can't help you. 對不起，我?guī)筒簧夏?。四、情態(tài)動詞

4、的用法：can (could)表示說話人能，可以,同意，準許,以及 客觀條件許可，could為can的過去式。Can you pass me the books? 你能給我遞一下書嗎 ？Could you help me, please?請問,你能幫助我嗎？What can you do? 你能干點什么呢？Can you be sure? 你有把握嗎？can和could只能用于現(xiàn)在式和過去式兩種時態(tài)，將來時態(tài)用be able to來表示。He could help us at all. 他完全可以幫助我們。With the teacher's help,I shall be able

5、to speak En glish correctly.由于老師的幫助，我將能準確地講英語。may (might)可以，表示說話人同意，許可或請求對方許可。You may take the book home.你可以把書帶回家去.May I come in? 我可以進來嗎？May I use your dictionary? 我可以用你的詞典嗎？You may put on more clothes. 你可以多穿點衣服 .He said he might lend us some mon ey.他說他可以借給我們一些錢。may 否定式為 may not, 縮寫形式是 mayn't.mi

6、ght是may的過去式，有兩種用法，一種表示過去式，一種表示虛擬語氣，使 語氣更加委婉，客氣或?qū)赡苄缘膽岩?。He told me he might be here on time.他說他能按時間來。Might I borrow some money now.我可以借點錢嗎 ?He might be alive. 他可能還活著。Must必須,應(yīng)該,一定,準是，表示說話人認為有必要做某事，命令,要求別人做某 事以及對事物的推測。must用來指一般現(xiàn)在時和一般將來時，過去式可用have to的過去式代替。I must fin ish my work today.我今天必須完成我的工作。You mu

7、st n't work all the time.你不能老是工作。Must I return the book tomorrow?我必須明天還書嗎？After such a long walk, you must be tired. 走了這么長的路，你一定困了。He must be the man I am look ing for.他一定是我要找的人。He had to go because of somebody's calli ng him that day.那天他要走是因為有人叫他。must + have +過去分詞,表示現(xiàn)在對過去事物的推測。He must have

8、told my pare nts about it.他一定把這件事情告訴我父母親了。He must have received my letter now.他現(xiàn)在一定收至 U我的信了。It's six o'clock already, we must have bee n late aga in.已經(jīng)六點鐘了，我們一定又遲到了。must和have to的區(qū)別：must表示說話人的主觀思想，have to表示客觀需要。You must do it now.你必需現(xiàn)在就干。（說話人認為必須現(xiàn)在干）I have to go now.我得走了。（客觀條件必須現(xiàn)在走）need需要多用在否

9、定式或疑問句中.單獨用為實義動詞Need I attend the meeting tomorrow?我需要明天參加會議嗎？You n eed not hand in the paper this week.這一周你不必交論文。need是一個情態(tài)動詞,他的用法完全和其他情態(tài)動詞一樣，但need還可當(dāng)作 實義動詞使用，這時need就象其他動詞一樣，有第三人稱，單復(fù)數(shù)，后面加帶to 的動詞等特性。 I n eed a bike to go to school.我上學(xué)需要一輛自行車。Do you need a dictionary? 你需要詞典嗎？She n eeds a n ecklace. 她需

10、要一條項鏈。need n't + have +過去分詞 表示過去做了沒必要做的事情。You need n't have take n it seriously.這件事情你不必太認真。dare敢 多用在否定或疑問句中。The little girl dare not speak in public.小女孩不敢在公眾面前說話。Dare you catch the little cat? 你敢抓小貓嗎？dare除用作情態(tài)動詞外，更多的是當(dāng)實義動詞使用，用法同實義動詞一樣，要考 慮人稱,單復(fù)數(shù)，時態(tài)等。Do you dare to walk in the dark?你敢黑夜走路嗎？He

11、 does n't dare to tell the teacher what happe ned that day.他不敢告訴老師那天發(fā)生的事。ought應(yīng)當(dāng)，應(yīng)該后面跟帶有to的動詞不定式。You ought to read these books if you want to know how to repair the motorcar. 如果你想知道如何修理汽車，你應(yīng)該讀這些書。You ought to bring the child here.你應(yīng)該把孩子帶來。ought + to have done 句型。指過去動作，表示一件事情該做而未做。You ought to ha

12、ve bee n here yesterday.你昨天就應(yīng)該來。ought not to have do ne 句型。表示一件不該做的事情卻做了。You ought not to have take n the book out of the read in g-room.你不應(yīng)該把書帶出閱覽室。will (would)決心,愿望。would為will的過去式,可用于各人稱。I'll do my best to catch up with them.我要盡全力趕上他們。I'll never do it again, that's the last time.我再不會做那

13、件事情了，這是最后一次。He said he would help me. 他說他會幫助我。will, would用于疑問句表示說話人向?qū)Ψ教岢稣埱蠡蛟儐?，用would比will更 婉轉(zhuǎn),客氣。It's hot. Will you open the windows? 天氣太熱了，你能打開窗戶嗎？Will you help me to work it out?你能幫我解這道題嗎？Would you like some coffee ？ 給你來點咖啡怎樣？Shall, should表示命令,警告,允諾,征求,勸告，建議驚奇。You should hand in the exercise b

14、ook.你應(yīng)該交作業(yè)本兒了。This should be no problem.這應(yīng)該沒問題。Shall we go now.我們現(xiàn)在可以走了嗎？Why should I meet him ？ 為什么我要見他？have to,不得不，必須，表示客觀條件只能如此，而must則表示主觀思想必須。I have to go now. 我現(xiàn)在得走了。I have to cook for my child.我得給孩子做飯。You must be here on time n ext time.你下次一定要按時來。We must go to get the timetable ourselves.我們一定要

15、自己去拿時刻表。情態(tài)動詞(Model Verbs)又稱為情態(tài)助動詞 (Model Auxil-iaries), 主要有can, may, must, could, might, shall , should, will, would, ought to, n eed, dare 等。情 態(tài)動詞與其他動詞連用表示說話人的語氣。情態(tài)動詞可表達建議、要求、可能和意愿等。情態(tài)動詞沒有人稱和數(shù)的變化。在大學(xué)英語考試中，情態(tài)動詞部分重點測試以下內(nèi)容：（1 ）情態(tài)動詞+動詞完成式:must have done（2 ）情態(tài)動詞+動詞進行式:must be doing（3 ）情態(tài)動詞+動詞完成進行式：must

16、have been doing（4）某些情態(tài)動詞的特殊用法：need一、情態(tài)動詞+動詞完成式情態(tài)動詞+動詞完成式即 情態(tài)動詞+ have + done分詞”表示對過去行為或 動作進行推測、評論或判斷。1. must have donemust have done表示對過去某事的肯定猜測。其否定或疑問形式都用can（could） 來表示.例如：Since the road is wet, it must have rained last night.He can ' t have missed the way. I drew him a map.“ The dict ionary has

17、 disappeared. Who could have take n it?”當(dāng)然對現(xiàn)在發(fā)生或?qū)戆l(fā)生的事情，要用must do表示猜測，否定為can' t do.He must un dersta nd that we mea n bus in ess.You must be hungry after a long walk.2. may / might have donemay / might have done 表示推測過去某事 也許”發(fā)生了 .may比might表 示的可能性在說話人看來稍大些。例如：I can ' ndi my keys. I may / might

18、 have left them at the school yesterday.3. could have done 在肯定句型中,往往用作委婉的批評.本應(yīng)該做什么,而沒做; 有時也用作猜測.You could have told us earlier.Tom could have take n the dicti on ary.4. ought to / should have done 和 ought not to / shouldnave dlbneought to / should have done 和 ought not to / shouldn' t have （用于對已

19、發(fā)生的情況表示 責(zé)備”不滿”分別表示 本應(yīng)該”和本不應(yīng)該”例如：1）With all the work finished, I should have gone to the party last night.2）You ought not to have made fun of him. He is not the one you laugh at but learn from.5. needn ' t have doneneedn' t have done表示過去做了某事，但沒有做的必要，意為 本沒必要”例如：You needn ' t have waken me up; I don ' t have to