情態(tài)動(dòng)詞

[例題]

1.It must have been around nine o'clock when I drove back home because it was already dark.

（當(dāng)我開車回家時(shí)，肯定九點(diǎn)左右了，因?yàn)樘煲讶�黑了。�?/P>

2.He fell asleep immediately last night; he must have been very tired.

（昨天晚上他躺下就睡著了，他一定是很累了。）

3.You needn't have done all those calculations! We have a computer to do that sort of thing.

（你沒(méi)有必要做這些計(jì)算！我們有計(jì)算機(jī)來(lái)做這種事情了。）

4.Mary couldn't have received my letter; otherwise she would have replied before now.

（Mary不可能收到我的信，不然她早就給我回信了。）

5.Comrade Li can't be in Beijing because I saw him in town only a few minutes ago.

（李同志不可能在北京，因?yàn)閹追昼娗拔以阪?zhèn)里看見他。）

6.You promised her a letter; you should have written days ago.

（你答應(yīng)過(guò)給她回信，你幾天前就應(yīng)該寫了。）

7.Must I get everything ready before they come?

（我必須在他們來(lái)到之前就要做好一切準(zhǔn)備嗎？）

8.It's quite early. We needn't worry about the time.

（還早呢。我們用不著擔(dān)心時(shí)間。）

9The road can be blocked[封堵].

（道路可能堵塞。）

[解析]情態(tài)動(dòng)詞must后面動(dòng)詞原形或完成式分別表示現(xiàn)在或過(guò)去情況的肯定猜測(cè)；情態(tài)動(dòng)詞can或could的否定形式后面跟動(dòng)詞原形或完成式分別表示對(duì)現(xiàn)在或過(guò)去情況的否定猜測(cè)；情態(tài)動(dòng)詞need的否定形式后面跟動(dòng)詞原形或完成式分別表示現(xiàn)在沒(méi)有必要或過(guò)去沒(méi)有必要做某事；should（或ought to）+“完成時(shí)”表示應(yīng)該在過(guò)去做而沒(méi)有做的動(dòng)作。