88 表示必須：must/ have to / have got to　Track 088

1）must和have to相近，都譯為“必須”。
例句
a. All applicants must take an entrance exam.
b. All applicants have to take an entrance exam.
2）have got to 主要用于口語中，不是很正式。
I have got to go now. I have a class in ten minutes.
3）要表示過去“必須”，我們要用had to，而must和have got to沒有過去式形式。
I had to study last Sunday.
4）注意否定意思：
don’t have to：不必要
mustn’t或must not：千萬不要，表示禁止。
例句
a. Tomorrow is Saturday. We don’t have to go to school.
明天是周六，我們不必上學。
b. You must not tell anyone my secret. Do you promise?
你千萬別告訴任何人我的秘密，你能答應我嗎？