課本中不會教你的[M]480　must和have to

480　must和have to

◎ must和have to都作“必須”解，一般情況下可通用，美式英語中用have to較多。

You must/have to do as you are asked. 要你怎么做，你就一定要怎么做。

① must表示說話人的個人意志、主觀看法或要求；或表示道義上的“必須”；have to表示“外界”的義務(wù)或客觀的需要，即別人認為某事要你去做，或者有一項協(xié)議、規(guī)定、法律等，要求你必須去做。

You must stop smoking. 你必須戒煙。（個人的主觀要求）

You have to follow these rules. 你必須遵守這些規(guī)則。（客觀環(huán)境有這種要求）

You must get up early. 你必須早起床。（強烈的主觀要求）

You have to get up early. 你有必要早起床。（客觀需要，比如要趕上某班車）

② must沒有過去時態(tài)和將來時態(tài)（但在間接引語中仍用 must）；have to的過去式為 had to，將來式為 will have to，表示將來“還得……”，今后“還有必要……”。

He had to hurry or he'd be late. 他必須趕緊走，否則要遲到了。（迫于時間很緊）

You will have to do more exercises. 你還得做更多的練習。（才能把所學的知識鞏固）

He must go there last night.

He had to go there last night.

他昨天晚上必須去那里。

He reminded me that I must be at the office by seven. 他提醒我必須在七點鐘前到辦公室。

③ 表示否定時，兩者的含義明顯不同。比較：

You have not to tell her the news. 你用不著把消息告訴她。

You must not tell her the news. 你決不可把消息告訴她。

④ have to的疑問式要用do，does 或 do 引起。

Have you to do it today？

Do you have to do it today？

你非得今天做這件事嗎？

⑤ have to的否定式有兩種。

You don't have to take an umbrella with you.

你不一定非得帶雨傘。

You haven't to take an umbrella with you.

We don't have to go to school on Sunday. 星期天我們不上學。（通常的情況）

We haven't to go to school today，because it's Teachers' Day. 今天我們不上學，因為今天是教師節(jié)。（特定的情況）

⑥ 注意“Do you have to…？”的肯定回答和否定回答。

A：Do you have to do housework？你必須做家務(wù)嗎？

B：Yes，I do./Yes，I have to./Yes，I've got to. 是的，必須做。

B：No，I don't have to./No，I haven't got to. 不，不必。