What do the modals in these statements express?

Варианты ответов и условие задания

1. It's a secret. You mustn't tell anybody about it.
2. Prohibition
3. Could you skate when you were 6 ?
4. Ability
5. Mary might come to our meeting, but we are not sure.
6. Possibility
7. Could you open the door, please?
8. Request
9. May I use your tablet?
10. Asking for permission
11. You should read this novel. It is really great.
12. Advice
13. I'm so happy. I don't have to go to work tomorrow.
14. Absence of necessity
15. It's getting late. I have to go.
16. Necessity