Question

Uso de must

Ex: I / drink / water

I must drink water
I mustn't drink water
Must I drink water

1°) Continue:

A) You / eat / less

You must eat less.
You mustn't eat less.
Must you eat less ?

B) She / work / everyday

She must work every day.
She mustn't work everyday.
Must she work every day ?

C) They / study / today

They must study today.
They mustn't study today.
Must they study today ?

2°) Deescreva as frases com must para have /has to.

Answer 1

A) You / eat / less 

You have to eat less.
You haven't eat less.
Have you eat less ?

B) She / work / everyday 

She has to work every day. 
She hasn't work everyday.
Has she work every day ?

C) They / study / today 

They have to study today.
They haven't study today.
Have they study today ?

Até onde eu entendo do inglês acredito que seja isto

Uma observação legal é que Have é usado para necessidade, e Must para obrigação
Exemplo
I have to go home.
“Eu preciso ir para casa” com sentido de “Eu tenho necessidade de ir para casa”.
I must go home.
“Eu preciso ir para casa” com sentido de “Eu tenho obrigação de ir para casa”.