Modal verbs

What is a modal verb?

We tend to use the modal verb "Should" for recommendations.

We use the modal verb "Have/has to" for internal obligations and expressing feelings.

The modal verb "Can" is only used to talk about ability.

INTERROGATIVE STRUCTURE: OUGHT TO

OUGHT TO YOU EAT THESE COOKIES?

The modal verb "mustn´t" is used to talk about internal obligations.

"Had better" is a modal verd to express that something is a good or bad idea.

The modal verb "Must" is used to talk about an obligation that comes internally from ourselves.

This sentence is correct:

My mother angrily says that I must clean my bedroom because it is a mess.

This sentence is wrong:

My dad should take a shower because he smells very bad.