He can run as fast as he want

May I ask you for a favour

We do not have to go to work. These days are holidays

He can run as fast as he want

I must do it by myself. No one will help me and I will not ask for help

Katy must not ride a horse. She has serious problems with her back

He must take care of his parents! They are sick and poor!

You may take my suitcase if you need to travel abroad

I can play football.

He can skate and ski.