It's forbidden to smoke on the plane. (you - must not)
You must not smoke on the plane.
We can't travel to Canada if we don't have a visa. (we - must)
We must have a visa to travel to Canada.
According to the rules and regulations, we have to wear masks. (we - must)
According to the rules and regulations, we must wear masks
Don't take any food in your baggage. (you - must not)
You must not take any food in your baggage.
You are not allowed to carry some objects with you. (you - must not)
You must not carry some objects with you