英語(yǔ)情態(tài)動(dòng)詞典型用法例釋

一、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(guò)去行為或動(dòng)作進(jìn)行推測(cè)、評(píng)論或判斷。

1. must have done表示對(duì)過(guò)去某事的肯定猜測(cè)。其否定或疑問(wèn)形式都用can(could) 來(lái)表示.

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

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

“The dictionary has disappeared. Who could have taken it?”

當(dāng)然對(duì)現(xiàn)在發(fā)生或?qū)?lái)發(fā)生的事情,要用must do 表示猜測(cè), 否定為can’t do.

He must understand that we mean business.

You must be hungry after a long walk.

2.may / might have done

may / might have done 表示推測(cè)過(guò)去某事“也許”發(fā)生了.may 比 might 表示的可能性在說(shuō)話人看來(lái)稍大些。例如：

I can’t find my keys. I may / might 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(píng). 本應(yīng)該做什么,而沒(méi)做; 有時(shí)也用作猜測(cè).

You could have told us earlier.

Tom could have taken the dictionary.

4. ought to / should have done和 ought not to / shouldn’t have done

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：

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 done

needn’t have done 表示過(guò)去做了某事，但沒(méi)有做的必要， 意為“本沒(méi)必要…”。

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

注：表示推測(cè)過(guò)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：

“I wonder how Tom knew about your past.”

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

二、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.

三、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(guò)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.

四、某些情態(tài)動(dòng)詞的特殊用法歸納

1. need

考試中主要測(cè)試 need 作情態(tài)動(dòng)詞與作實(shí)義動(dòng)詞的區(qū)別.

情態(tài)動(dòng)詞need與實(shí)義動(dòng)詞need 在時(shí)態(tài)、肯定、否定結(jié)構(gòu)上的對(duì)比見(jiàn)下表。

時(shí)態(tài) 情態(tài)動(dòng)詞need 實(shí)義動(dòng)詞 need

現(xiàn)在時(shí) He need (needn’t) do

Need he do….? He needs (doesn’t need) to do

過(guò)去時(shí) He needed (didn’t need) to do

將來(lái)時(shí) He need (needn’t) do

Need he do….? He will (not) need to do

注: need 一般用于否定句或疑問(wèn)句.

2. dare

考試中主要測(cè)試dare作情態(tài)動(dòng)詞和作實(shí)義動(dòng)詞的區(qū)別。

情態(tài)動(dòng)詞dare 與實(shí)義動(dòng)詞dare 在時(shí)態(tài)、肯定、否定、疑問(wèn)結(jié)構(gòu)上的對(duì)比如下：

句型   情態(tài)動(dòng)詞dare 實(shí)義動(dòng)詞 dare

肯定句 現(xiàn)在時(shí) dare to 少用

過(guò)去時(shí) dare to 少用 現(xiàn)在時(shí) dare/dares to do

過(guò)去時(shí) dared to do

否定句 現(xiàn)在時(shí) daren’t/dare not do

過(guò)去時(shí) dared not do 現(xiàn)在時(shí) do/does not dare (to) do

過(guò)去時(shí) did not dare (to) do

疑問(wèn)句 現(xiàn)在時(shí) Dare he do?

過(guò)去時(shí) Dared he do? 現(xiàn)在時(shí) Do you/Does he dear (to) do?

過(guò)去時(shí) Did he dare (to) do

3. can 和 may

考試中主要測(cè)試can，may或could，might表示可能性的區(qū)別及對(duì)may構(gòu)成的疑問(wèn)句的回答。

（1）can, could, may, might都可以表示可能性.can, could表示潛在的可能性或理論上或邏輯判斷上存在的可能性；而may, might則表示事實(shí)上的可能性。此外，can還具有“有能力”的意思，而may與might則不具此意。例如：

According to the weather forecast, it may rain tomorrow.

Any man with a little sense can see that he is wrong.

（2）May I / we …？這一類(lèi)疑問(wèn)句的肯定回答為Yes, please.或Certainly；否定回答為Please don’t.或No, you mustn’t. 例如：

“May we leave now?” “No, you mustn’t. You haven’t finished your home work yet.”

4. can 和 be able to

can 與 be able to 都可以表示能力，但兩者在用法上有點(diǎn)差異：can (could)表示主觀能力，不表示意愿，它的將來(lái)時(shí)用will be able to; be able to表示主觀意愿，強(qiáng)調(diào)要克服困難去做某事。例如：

1）My grandma is over seventy, but she can still read without glasses.

2）He is able to give up his bad habits.

5. must 和 have to

must 和 have to 都可以表示“必須”，但有幾點(diǎn)區(qū)別：

（1）must 強(qiáng)調(diào)“內(nèi)在的職責(zé)”、“義務(wù)”，而have to 強(qiáng)調(diào)“外界壓力”、“不得已而為之”。

（2）have to可用于多種時(shí)態(tài)，而must一般用于現(xiàn)在時(shí)，其過(guò)去時(shí)與將來(lái)時(shí)分別由had to與shall / will have to代替。

（3）在回答must引起的問(wèn)題時(shí)，如果是否定的答復(fù)，不能用mustn’t，而要用needn’t或don’t have to，因?yàn)?/SPAN>mustn’t是“一定不要”、“一定不能”的意思。例如：

1）You must come to the classroom before eight.

2）It is raining hard outside, but I have to leave now.

3）“Must we do it now?” “No, you needn’t.”

6. used to +do, be used to +doing和be used to +do

（1）used to +v意為“過(guò)去常常”，“過(guò)去一直”；be used to +v-ing / n（名詞）意為“習(xí)慣于”；be used to +v意為“被用來(lái)（做某事）”。

（2）used to只表示過(guò)去，而be used to +v-ing / n可表示現(xiàn)在、過(guò)去或?qū)?lái)。例如：

1）He used to smoke. Now he doesn’t.

2）He’s quite used to hard work / working hard.

3）The knife is used to cut bread.

7．用作情態(tài)動(dòng)詞的其他短語(yǔ)

would rather, would sooner, would (just) as soon, had rather, had better, had sooner, can not but, may (just) as well等可用作情態(tài)動(dòng)詞。例如：

1）The soldier would sooner die than surrender.

2）The brave soldier would as soon die as yield to such an enemy.

3）I’d rather walk than take a bus.

4）If you don’t like to swim, you may just as well stay at home.

注：這些短語(yǔ)后一般直接跟動(dòng)詞原形.would (had) rather, would (had) sooner, would (just) as soon后可跟that 引導(dǎo)的從句，that 常省去，從句要用虛擬語(yǔ)氣。對(duì)現(xiàn)在和將來(lái)的假設(shè)用過(guò)去時(shí)，對(duì)過(guò)去的假設(shè)用過(guò)去完成時(shí)。例如：

1）I would rather you came on Sunday.

2）I would sooner you hadn’t asked