第四節(jié) 情態(tài)動(dòng)詞

情態(tài)動(dòng)詞 (Model Verbs) 又稱為情態(tài)助動(dòng)詞 (Model Auxiliaries)。英語中助動(dòng)詞主要有兩類：一是基本助動(dòng)詞，如have, do, be；二是情態(tài)助動(dòng)詞，如may, must, need等。情態(tài)動(dòng)詞與其他動(dòng)詞連用表示說話人的語氣。情態(tài)動(dòng)詞可表達(dá)建議、要求、可能和意愿等。情態(tài)動(dòng)詞沒有人稱和數(shù)的變化。在英語的各種考試考試中，現(xiàn)在一個(gè)明顯的趨勢(shì)是呈現(xiàn)出復(fù)雜的結(jié)構(gòu)。根據(jù)我們對(duì)歷年來試卷的分析，情態(tài)動(dòng)詞部分重點(diǎn)測(cè)試以下內(nèi)容：

（1）情態(tài)動(dòng)詞+行為動(dòng)詞完成式
（2）情態(tài)動(dòng)詞+行為動(dòng)詞進(jìn)行式
（3）情態(tài)動(dòng)詞+行為動(dòng)詞完成進(jìn)行式
（4）某些情態(tài)動(dòng)詞的特殊用法

一、一般情態(tài)動(dòng)詞

1、情態(tài)動(dòng)詞的完成式：

⑴ 情態(tài)動(dòng)詞的完成式即“情態(tài)動(dòng)詞+ have + v-ed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。如：

Since the ditch(溝，溝渠) is full of water, it must have rained last night. 溝渠里的水都滿了，想必昨晚一定下雨了。
You couldn’t have met my grandmother. She died before you were born.你不可能遇到我奶奶，因?yàn)樗缭谀愠錾熬退懒恕?br>I can’t find my keys. I may / might have left them at the school yesterday.我找不到鑰匙了，也許昨天丟到學(xué)校了吧。

⑵ 當(dāng)情態(tài)動(dòng)詞完成式是由ought to / should加完成式或否定式ought not to / shouldn’t加完成式時(shí)，是表示對(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：

You ought not to make fun of him. He is not the one you laugh at but learn from.你本不應(yīng)該取笑他的。他不是你嘲笑是而恰恰是你應(yīng)該學(xué)習(xí)的一個(gè)人。
You should have finished your compositon(寫作，作文) by yesterday.你本應(yīng)該昨天前就把作文寫完的。

⑶ needn’t have v-ed

needn’t have v-ed 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 wakened me up; I don’t have to go to work today.你本沒必要把我叫醒，因?yàn)槲医裉觳簧习唷?br>
注：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。

2、情態(tài)動(dòng)詞的進(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 + v-ing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：

The light in his study is still on; he must be working now.他書房的燈還亮著，想必他現(xiàn)在還在工作。
She shouldn’t be working like that. She is still very weak.她不應(yīng)該這樣干,她身體還這樣弱.
He can’t be telling the truth. 他說的不可能是真話.

3、情態(tài)動(dòng)詞的完成進(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：

They are sweating all over. They must have been working in the fields.他們渾身是汗，準(zhǔn)是在地里一直干活來著。
They may have been discussing this suggestion all the morning.今天上午他們可能一直在討論這個(gè)建議來著。

二、特殊情態(tài)動(dòng)詞

除了上述的基本情態(tài)動(dòng)詞之外，還有一些如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。
The soldier would sooner die than surrender(投降). 這個(gè)戰(zhàn)士寧死不降。
If you don’t like to swim, you may just as well stay at home. 如果你不喜歡游泳，你也可以待在家里啊。

這些短語后一般直接跟動(dòng)詞原形。但是當(dāng)would (had) rather, would (had) sooner, would (just) as soon后可跟that 引導(dǎo)的從句時(shí)，從句就要用虛擬語氣。對(duì)現(xiàn)在和將來的假設(shè)用過去時(shí)，對(duì)過去的假設(shè)用過去完成時(shí)。例如：

I would rather you went home right now.我倒寧愿你現(xiàn)在立刻回家去。
I would sooner you hadn’t asked me to speak yesterday. 我倒寧愿你昨天沒邀請(qǐng)我講話。

三、情態(tài)動(dòng)詞中應(yīng)特別注意的典的型結(jié)構(gòu)

They must be in the library, aren’t they? 他們一定還在圖書館，對(duì)吧？
They must have gone to the library, haven’t they? 他們一定去圖書館了，對(duì)吧？
They must have been to the library yesterday, didn’t they? 他們昨天一定去了圖書館，是不是？
Let me do it, will you? 讓我來做，好么？Let me help you, may I? 請(qǐng)讓我?guī)湍?，可以嗎?br>Don’t move, will you? 請(qǐng)你別動(dòng)！
Go quickly, can you? 你能不能快點(diǎn)？
Let’s go for a walk, shall we? 咱們?nèi)ド⒉?，好么?br>He used to live in the countryside, didn’t/usedn’t he? 他過去住在農(nóng)村，對(duì)吧？