Can’t: Used to express inability or impossibility to do something. Example: I can’t swim.

Could: Used to express ability or possibility in the past or present. Example: I could swim when I was younger.

Couldn’t: Used to express inability or impossibility in the past. Example: I couldn’t swim when I was younger.

Must: Used to express necessity or obligation. Example: I must finish my homework before I can go out.

May: Used to express permission or possibility. Example: May I go to the bathroom?

Might: Used to express possibility or uncertainty. Example: I might go to the party tonight.