- pronunciation:
- muhst
- features:
- Note
| part of speech: |
verb |
| definition 1: |
When you must do something, it means that it is completely necessary to do. You have to do it.
Humans must breathe air in order to live.Fish must have clean water. If their water gets too dirty, they will die. |
| definition 2: |
If you must do something, you have to do it because of a rule, a command, or a law. If someone says you must not do something, it means you are not allowed to do it.
The teacher said I must get my mom's permission or I can't go on the field trip.A baby must ride in a special seat when they are in a car. If they don't, it is breaking the law.Many signs at the zoo say that visitors must not feed the animals. |
| definition 3: |
If your mother says that you must not pull the cat's tail, it means that she is commanding you not to pull the cat's tail. If she says you must put your clothes away, she is telling you to put your clothes away. If you don't put your clothes away after this, you will get into trouble.
My dad said I could go out with my friends, but I must be back home before six o'clock. |
| definition 4: |
We often use "must" when we don't really know something as a fact, but we are very sure about it anyway.
The kid in the giraffe costume must be Marcus. Nobody else is that tall, and I don't see him anywhere else in the room.You must have washed your hair this morning. It's still wet. |
must or have to?
Have to and
must share the meaning of necessity to do something.
Have to is used more often in everyday conversation.
Must is more often used in writing or in a formal situation. But for the meaning of
must in a sentence such as
You must be joking!, both
have to and
must are very common in conversation. You need to be careful, though, to choose between
have to and
must when your sentence uses
not. In negative sentences,
have to and
must have different meanings, as you can see in the examples below.
Compare:
- You have to leave tomorrow.
- You must leave tomorrow.
- You do not have to leave tomorrow. (It is not necessary for you to leave tomorrow. You can leave tomorrow if you want, or you can stay.)
- You must not leave tomorrow. (You do not have permission to leave tomorrow.)