This document discusses the uses of different modal verbs to convey obligation, prohibition, advice, and necessity. It states that "must" and "mustn't" are used to talk about obligation and prohibition, "should" and "shouldn't" are used to give advice, and "have to" and "don't have to" are used to talk about obligation and what is not necessary, respectively. Examples are provided for how each modal verb is used in sentences.

1. MUST and SHOULD
We use
MUST
to talk about …
OBLIGATION and PROHIBITION
Must (Obligation): I must do my homework.
Mustn’t (Prohibition): You mustn’t walk on the grass in the
park. It is forbidden.
We use
SHOULD
to give …
ADVICE:
Should: You should eat healthy food. It’s good for you.
Shouldn’t: You shouldn’t stay up till late. It’s bad for you.

2. HAVE TO and DON’T HAVE TO
We use
HAVE TO
to talk about …
OBLIGATION
Have to: Police officers have to wear a uniform.
We use
DON’T HAVE TO
to say that something is …
NOT NECESSARY:
Don’t have to: You don’t have to pick me up. I’ll take a
taxi.