考研英語：語法大全(情態(tài)動(dòng)詞-must)
must
must的詞義
must表示"必須"或"應(yīng)當(dāng)"。如：
I must leave at 9:00我必須在九點(diǎn)鐘離開這里。
Soldiers must obey orders.士兵必須服從命令。
You must get to the stallion before three o'clock. 你必須在三點(diǎn)鐘以前到達(dá)車站。
You must come earlier tomorrow.你明天得早點(diǎn)來。
must的否定式
must的否定形式must not表示"不應(yīng)該"或
"不許可"，語氣比較強(qiáng)烈。如：
We mustn't waste our time. 我們不應(yīng)該浪費(fèi)我們的時(shí)間。
Passengers must not walk across the railway line.旅客不要橫穿鐵路。
You mustn't miss that modern ballet，It is extremely good. 你可不要錯(cuò)過這個(gè)現(xiàn)代芭蕾舞劇，它好極了。
One must not divorce oneself from the masses.不應(yīng)該脫離群眾。
[注]說"不必"須用need not。如：
Must we hand in our exercises today? -No，You needn't.我們必須今天交練習(xí)嗎? --不，不必今天交。
must也可表示過去
must只有現(xiàn)在式，通常用以表示現(xiàn)在，但有時(shí)也可以表示過去(多用在間接引語中)。如：
He told us we must all be ready by nine.他告訴我們在九點(diǎn)鐘以前都得準(zhǔn)備好。
It was too late to go back，we must go on.太晚了，回不去了，我們只有繼續(xù)往前走。
[注] have to (必須)則可以表示各種時(shí)間。如：
I am afraid You will have to wait a while.我看你得等一會(huì)兒。
At every step I had to pull my legs out of the snow.我每走一步都得將雙腿從雪中拔出來。
must也可表示說話人對事物的推測
但比may肯定得多，相當(dāng)于漢語的"一定"或"準(zhǔn)是"。如：
He must be in the library now. 他現(xiàn)在準(zhǔn)是在圖書館。
The old man must be over seventy now.那老人準(zhǔn)有七十多歲了。
She must know how to do farm work. 她一定懂得怎樣干農(nóng)活。
You ate very little at breakfast today. You must be hungry now.
你今天早餐吃得很少，現(xiàn)在一定餓了。
[注] must加動(dòng)詞原形的進(jìn)行式，也可表示對現(xiàn)在發(fā)生的動(dòng)作的推測，有"一定"、"準(zhǔn)是"的意思。如：
She must be working on the experimental plot.她現(xiàn)在一定在試驗(yàn)田里工作。
must加動(dòng)詞原形的.完成式
說明對過去事物的推測，表示"一定"或"準(zhǔn)是"的意思。如：
I mailed the letter two weeks ago. She must have received it.
我是兩星期以前發(fā)的信，她一定已經(jīng)收到了。
She must have studied English before. 她以前一定學(xué)過英語。
How did you know about it? Somebody must have told you. 你怎么知道這事的?一定有人告訴你了。
【考研英語：語法(情態(tài)動(dòng)詞-must)】相關(guān)文章：
考研英語：語法大全(情態(tài)動(dòng)詞-have to)07-07
考研英語：語法大全(情態(tài)動(dòng)詞-dare/need)07-07
考研英語：語法大全(情態(tài)動(dòng)詞特征及變化)07-07
2016考研英語語法詳解：情態(tài)動(dòng)詞03-25
考研英語：語法大全(情態(tài)動(dòng)詞-will,would,ought)05-05
考研英語：語法大全(情態(tài)動(dòng)詞-can,could)05-05
考研英語：語法大全(情態(tài)動(dòng)詞-may,might)05-05
考研英語情態(tài)動(dòng)詞10-07