must and have to

must and have to

We use must and must not in formal rules and regulations and in warnings:

I must phone Steve when I get home. I said I?d call him last night, but I forgot.

We can also use I must... to remind ourselves to do something:

We must get together more often.We mustn't leave it so long next time.

In spoken English we often use must and mustn't (= must not) to propose a future arrangement, such as a meeting or social event, without making detailed plans:

The government must not be allowed to appoint judges.

Bookings must be made at least seven days before departure.

something that happened in the past we use must + have + past participle:

That's not Kate's car. She must have borrowed it from her parents.

I was wrong about the meeting being today. It must be happening next Friday. a present situation we use must be, or have (got) to be in informal speech

Their goalkeeper has got to be at least two metres tall! (or ...must be...)

John wasn't at home when I went round. He must have had to go out unexpectedly. Note that we can't say 'must have to,or ,must have got to/ must've got to,(but we can say must've had to).