must · modal
must (NECESSARY)
A2 used to say that it is necessary or important that something happens or is done
Dictionary examples:
I must study English, or my brain will forget how to talk! (0.0)
You must brush your teeth, or they'll run away! (0.0)
We must turn off the TV, or it will eat all our time! (0.0)
I must admit I'm very tired. (19.3)
Meat must be cooked thoroughly. (23.3)
Luggage must not be left unattended. (46.0)
must (LIKELY)
B2 used to show that you think something is very likely or certain to be true
Dictionary examples:
There's no food left - they must have eaten it all. (12.5)
Harry's been driving all day - he must be tired. (20.7)
She must be very wealthy. (22.2)
It must have been very upsetting for her. (44.7)