must 的用法

1. 表示 “必须”, “一定要”， “得”
You must answer all the questions. 你必须回答全部问题。
I must remember to go to the bank today. 我一定要记着今天得去银行。
You must show the guard your pass when you enter this building. 要进入大楼你必须向警卫出示通行证。

2. 否定形式表示“不得”，”不准”, “禁止”
Cars must not park in front of the entrance. 入口处不得停放汽车。
We mustn't be late. 我们不能迟到。
You must not open the oven before the cake is ready. 蛋糕未烤好前你不得打开烤箱。

3. must be表示推想, 可译为 “一定”, “准是”等。
She must be asleep. 她一定睡着了。
You must be hungry after such a long walk. 走了这么远一段路，你一定饿了吧。