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

1）must和have to相近，都译为“必须”。
例句
a. All applicants must take an entrance exam.
b. All applicants have to take an entrance exam.
2）have got to 主要用于口语中，不是很正式。
I have got to go now. I have a class in ten minutes.
3）要表示过去“必须”，我们要用had to，而must和have got to没有过去式形式。
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：千万不要，表示禁止。
例句
a. Tomorrow is Saturday. We don’t have to go to school.
明天是周六，我们不必上学。
b. You must not tell anyone my secret. Do you promise?
你千万别告诉任何人我的秘密，你能答应我吗？