在英语中，情态动词表示说话者对某个动作或状态的看法、想法或主观设想。其中 “must” 和 “have to” 都表示 “必须” 做某事，一个表示 “主观义务”，一个强调 “客观要求”。看视频，学习 “must” 和 “have to” 之间的主要区别。
Hi, this is Kee from BBC Learning English. Today, I'm going to tell you the differences between must and have to.
Both must and have to talk about obligations. However!
Now, we use have to when we talk about obligations others decide for us. It's a law or a rule, so it cannot be changed. For example: At BBC, we have to show our passes to enter the building. This is a rule decided by the BBC.
On the other hand, we use must when we talk about obligations we decide for ourselves or others. For example, my boss might say to me: You must be more organised. Or, I might say to myself: I must exercise more often.
Must and have to
Both must and have to talk about obligations. Both are followed by an infinitive without 'to'.
两者都用来描述 “义务”，而且两者后面都直接跟动词原形，即 “must do something” 和 “have to do something”。
1. Have to
Have to' is used for obligations that others decide for us. These are often laws or rules and so cannot be changed.
“Have to” 用来谈论 “客观要求”。这些通常是法律或规定，因此不能改变。
We have to show our passes to enter the building.
You have to smoke outside. Smoking is not allowed inside.
She has to have a license before she drives.
We use must to talk about obligations we decide for ourselves or others.
我们用 “must” 来谈论“主观义务”，指对自己或他人的要求。
You must be more organised.
I must exercise more often.
We must clean the house today.