一．情態(tài)動(dòng)詞的語法特征

1. 情態(tài)動(dòng)詞不能表示正在發(fā)生或已經(jīng)發(fā)生的事情，只表示期待或估計(jì)某事的發(fā)生。

2. 情態(tài)動(dòng)詞 除ought 和have 外，后面只能接不帶to 的不定式。

3. 情態(tài)動(dòng)詞沒有人稱，數(shù)的變化，即情態(tài)動(dòng)詞第三人稱單數(shù)不加-s。

4. 情態(tài)動(dòng)詞沒有非謂語形式，即沒有不定式、分詞、等形式。

情態(tài)動(dòng)詞的分類和意義

意義情態(tài)動(dòng)詞

can, may, might, could, would, will, shall, must, should, ought to, used to

二．情態(tài)動(dòng)詞的基本用法

1. can (could)

1) 表示能力，could主要指過去時(shí)間。例如：

① Two eyes can see more than one.   兩只眼比一只眼看得清。

② Could the girl read before she went to school?   這女孩上學(xué)前能識(shí)字嗎？

2) 表示可能（理論上或是邏輯判斷上）。例如：~,>_K

① He can't (couldn't) have enough money for a new car.  他不可能有足夠的錢買新車。

② You mustn't smoke while you're walking around in the wood. You could start a fire.  在林子里走時(shí)勿吸煙，那樣可能會(huì)引起火災(zāi)。

3) 表示允許。例如：

① Can I have a look at your new pen?   我可以看一看你的新鋼筆嗎？

② He asked whether he could take the book out of the reading-room.  他問他可不可以把書帶出閱覽室。

4) 表驚異、懷疑、不相信等態(tài)度。主要用于否定句、疑問句或感嘆句中。例如：

① Where can (could) they have gone to?   他們會(huì)去哪兒了呢？

② How can you be so careless?   你怎么這么粗心？

5) 比較委婉客氣地提出問題或陳述看法。例如：

① Can (Could) you lend me a hand?   幫我一把好嗎？.

② I'm afraid we couldn't give you an answer today.  恐怕我們今天不能給你答復(fù)。

2．may (might)

1) 表允許，might可以指過去時(shí)間，也可指現(xiàn)在時(shí)間，語氣更委婉。例如：

① You may take whatever you like.你喜歡什么就拿什么。

② May (Might) I ask for a photo of your baby? 我可以要一張你寶寶的照片嗎？

在回答以may引起的問句時(shí)，多避免用這個(gè)詞，而用其它方式，如Yes, please. / Certainly. / Please don't. / You'd better not. / No, you mustn't.等，以免顯得太嚴(yán)峻或不客氣。

2) 表可能（事實(shí)上）�？梢灾高^去時(shí)間，也可以指現(xiàn)在時(shí)間，但語氣更加不肯定。例如：

① He may be at home.   他可能在家。\

② She may not know about it.   她可能不知道這件事。

must

1) 表示義務(wù)。意為"必須"（主觀意志）。例如：

① We must do everything step by step.   我們一切都必須循序漸進(jìn)地做。

② --Must we hand in our exercise books now?我們現(xiàn)在就要交練習(xí)本嗎？

--No, you needn't. / No, you don't have to.   不必。

4) 表示揣測(cè)。意為"想必、準(zhǔn)是、一定"等，只用于肯定句。例如：

① He must be ill. He looks so pale.   他準(zhǔn)是病了。他的臉色蒼白。

② She's wearing a diamond necklace. She must have a lot of money. 她戴著鉆石項(xiàng)鏈，一定很有錢。:

3．shall

1) 表征詢意見，用于第一、第三人稱疑問句。例如：

① Shall I get you some tea?   我給你點(diǎn)茶好嗎？

② Shall the boy wait outside?  讓那男孩在外面等嗎？

2) 表說話人的意愿，有"命令、允諾、警告、決心"等意思，用于第二、第三人稱陳述句。例如：

① You shall do as I say. 按我說的做。（命令）

② You shall have my answer tomorrow. 你明天可以得到我的答復(fù)。（允諾）

③ He shall be sorry for it one day, I tell you. 有一天他會(huì)后悔的，我告訴你。（警告）

④ Nothing shall stop us from carrying out the plan. 什么也不能阻止我們執(zhí)行這項(xiàng)計(jì)劃。（決心）

4．will

1) 表意愿，用于各種人稱陳述句。例如：

① I will do anything for you.   我愿為你做任何事。

② None is so blind as those who won't see.   不愿看的人眼最瞎。

③ If you will read the book, I'll lend it to you.  如果你愿意讀這本書，我會(huì)把它借給你。

2) 表請(qǐng)求，用于疑問句。例如：

① Will you close the window?   請(qǐng)你把窗戶關(guān)上好嗎？

② Won't you drink some more coffee?   再來一點(diǎn)咖啡好嗎？

3) 表示某種傾向或習(xí)慣性動(dòng)作。例如：

① Fish will die out of water.   魚離開水就不能活。

② The door won't open.  這門打不開。

5. should

1) 表義務(wù)。意為"應(yīng)該"（某件事宜于做），用于各種人稱。例如：

① You should be polite to your teachers.   你對(duì)老師應(yīng)該有禮貌。

② You shouldn't waste any time.   你不應(yīng)該浪費(fèi)時(shí)間。

2) 表推測(cè)，意為"想必一定、照說應(yīng)該、估計(jì)"等。例如：

① The film should be very good as it is starring first-class actors.  這部新電影是一流演員主演的，估計(jì)拍得很好。

② They should be home by now.   照說他們現(xiàn)在應(yīng)當(dāng)已經(jīng)到家了。

3)（表示不確定）萬一。例如：

① If I should see him, I'll tell him. 萬一我見到他，我就告訴他。

② If it should rain tomorrow, the sports meeting would be postponed. 萬一明天下雨,比賽就延期舉行。"

6.  would

1) 表意愿。例如：:

① They would not let him in because he was poorly dressed. 他們不讓他進(jìn)去因?yàn)樗�衣著破舊。

② I said I would do anything for you.   我說過我愿意為你做任何事。

2) 表委婉地提出請(qǐng)求、建議或看法。例如：

① Would you mind cleaning the window?   請(qǐng)把窗戶擦一下好嗎？

② They wouldn't have anything against it.   他們不會(huì)有什么反對(duì)意見。

3) 表過去反復(fù)發(fā)生的動(dòng)作或過去的一種傾向。例如：:

Every time she was in trouble, she would go to him for help.   她每遇到麻煩都會(huì)向她求助。他告訴我盒子打不開了。

7.ought to

1) 表義務(wù)，意為"應(yīng)該"（因責(zé)任、義務(wù)等該做），口氣比should稍重。例如：

① You are his father. You ought to take care of him.你是他父親，應(yīng)當(dāng)管他。

② You oughtn't to smoke so much.   你不應(yīng)該抽這么多煙。

2) 表推測(cè)，暗含很大的可能，語氣較弱。例如：

① Han Mei ought to know his telephone number. 韓梅該知道他的電話號(hào)碼。

② There's a fine sunset; it ought to be a fine day tomorrow.  今天有晚霞，明天應(yīng)該是個(gè)好天。

8. used to

表示過去的習(xí)慣動(dòng)作或狀態(tài)，現(xiàn)在不復(fù)發(fā)生或存在。疑問式和否定式有兩種。例如：i

① There used to be a building at the street corner, but it has been pulled down.   街道拐角處過去有座樓房，現(xiàn)在拆了。

② I usedn't (didn't use) to smoke.   我過去不抽煙。j }F

③ Used you (Did you use) to go to school on foot? 你過去常步行去學(xué)校嗎？

9.特殊情態(tài)動(dòng)詞need和dare的用法：

need和dare既可用作情態(tài)動(dòng)詞，也可用作實(shí)義動(dòng)詞。用作情態(tài)動(dòng)詞時(shí)，主要用于否定句和疑問句。用作實(shí)義動(dòng)詞時(shí)，可用于各種句式。

1) 用作情態(tài)動(dòng)詞。例如：|

① You needn't telephone him now.   你現(xiàn)在不必打電話給他。

② I don't think you need worry.   我想你不必發(fā)愁。

③ She dare not go out alone at night.   她晚上不敢一個(gè)人出去。

④ How dare you say I'm unfair?   你竟敢說我不公平？_

2) 用作實(shí)義動(dòng)詞。例如：

① You don't need to do it yourself.   你不必親自做這件事。

② We need to tell them the news.   我們需要把這消息告訴他們。

③ The table needs painting (to be painted.).   桌子需要油漆一下。

④ We should dare to give our own opinion.   我們要敢于提出自己的觀點(diǎn)。

⑤ He did not dare (to) look up.   他不敢抬頭看。

⑥ I dare say he'll come again.   我想他會(huì)再來的。

【注意】（I dare say…為固定習(xí)語）

◆ 難點(diǎn)突破

1. 情態(tài)動(dòng)詞后跟完成式和進(jìn)行式的用法

1) 情態(tài)動(dòng)詞+動(dòng)詞完成式

情態(tài)動(dòng)詞+動(dòng)詞完成式即"情態(tài)動(dòng)詞+ have + done分詞"，表示對(duì)過去行為或動(dòng)作進(jìn)行推測(cè)、評(píng)論或判斷。

must have done 表示對(duì)過去某事的肯定猜測(cè)。其否定或疑問形式都用can(could) 來表示。  例如： 

① Since the road is wet, it must have rained last night.

② He can't have missed the way. I drew him a map.

③ The dictionary has disappeared. Who could have taken it?

當(dāng)然對(duì)現(xiàn)在發(fā)生或?qū)�來發(fā)生的事情,要用must do 表示猜測(cè), 否定為can't do。例如：

④ He must understand that we mean business.

⑤ You must be hungry after a long walk.

may / might have done表示推測(cè)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：

⑥ I can't find my keys. I may / might have left them at the school yesterday.

could have done 在肯定句型中, 往往用作委婉的批評(píng). 本應(yīng)該做什么,而沒做; 有時(shí)也用作猜測(cè)。例如：

⑦ You could have told us earlier.

⑧ Tom could have taken the dictionary.

ought to / should have done和 ought not to / shouldn't have done用于對(duì)已發(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：

⑨ With all the work finished, I should have gone to the party last night.

⑩ You ought not to have made fun of him. He is not the one you laugh at but learn from.

needn'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：

⑾ You needn't have waken me up; I don't have to go to work today.

【注意】表示推測(cè)過去某動(dòng)作發(fā)生的可能性時(shí)，就表示的可能性程度而言，must最大，could其次，may更次之，might最小。例如：

    ⑿ ---I wonder how Tom knew about your past. 

---He must / could / may / might have heard of it from Mary.

2) 情態(tài)動(dòng)詞+動(dòng)詞進(jìn)行式

情態(tài)動(dòng)詞+行為動(dòng)詞進(jìn)行式（即情態(tài)動(dòng)詞+ be + doing形式），表示推測(cè)或評(píng)論某動(dòng)作現(xiàn)在是否正在進(jìn)行。例如：

① He must be playing basketball in the room.

② She may be staying at home.

3) 情態(tài)動(dòng)詞+動(dòng)詞完成進(jìn)行式

情態(tài)動(dòng)詞+行為動(dòng)詞完成進(jìn)行式（即情態(tài)動(dòng)詞+ have been + v-ing形式），表示推測(cè)或評(píng)論過去某動(dòng)作是否正在進(jìn)行或一直在進(jìn)行。例如：

① They should have been meeting to discuss the problem.

② He may / might have been buying stamps in the post office when you saw him.|