1. Modal verbs

5. You must do it !

6. He had to go there!

7. He ought to help her!

9. They can run very fast!

10. I could run very fast when I was young!

11. I won’t be able to go to the theatre tomorrow!

14. Need I wash up?
-No, you needn’t!

15. Can
Ability, possibility, probability, doubt, surprise
Could
Ability, possibility in the past; offers, request
May
Probability, asking and giving permission
Must
Obligation, prohibition, necessity
Have to
Necessity, moral duty
Be to
Plans and arrangements
Ought to
Moral duty
Need
Necessity (in questions and negative sentences)
Should
Advice, moral duty, obligation