I Modal Verb Məst Mʌst Visitors Report Reception

• all visitors must report to reception.
• cars must not park in front of the entrance (= it is not allowed).
• i must ask you not to do that again.
• you mustn't say things like that.

must

Verb Forms

1. used to say that something is necessary or very important (sometimes involving a rule or a law)
• All visitors must report to reception.
• Cars must not park in front of the entrance (= it is not allowed).
• I must ask you not to do that again.
• You mustn't say things like that.
• I must go and get the kids from school.
• I must admit (= I feel that I should admit) I was surprised it cost so little.
• Must you always question everything I say? (= it is annoying)
• ‘Do we have to finish this today?’ ‘Yes, you must.’
2. used to say that something is likely or logical
• NOTE AT need
  https://www.oxfordlearnersdictionaries.com/definition/english/need_1#need_topg_2
• You must be hungry after all that walking.
• He must have known (= surely he knew) what she wanted.
• I'm sorry, she's not here. She must have left already (= that must be the explanation).
3. used to recommend that somebody does something because you think it is a good idea
• You simply must read this book.
• We must get together soon for lunch.
4. used to say that somebody may do something but you do not really want them to
• ‘Can I smoke?’ ‘If you must.’
• It's from my boyfriend, if you must know.
5. used to tell people that something is so good or interesting that they should see, read, get it, etc.
• Sydney is one of the world's must-see cities.
• The magazine is a must-read in the show business world.
• This is on my must-do list.
• a must-have for any fan
6. in certain situations it is necessary for you to do something that you do not like or enjoy

Word Origin

• Old English mōste, past tense of mōt ‘may’, of Germanic origin; related to Dutch moeten and German müssen.