1. jonathan may/might/ can/ should ski really well and he often wins his races 2. i can/must/ might/ought to go to the party but i'm still not sure 3. i think you should/ must/ shall/will go out more and meet new people 4. it's dangerous to go into deep water if you can't/ shouldn't/ mustn't/ mightn't swim 5. i can/ mustn't /might/ should go out later with my parents but i don't really know 6. all passengers must/mustn't/ might/ can't remain in their seats and must/mustn't/ might/can use their mobile phones 7. you can/ should/ must/ might wear a uniform when you're in the army 8. she can't /may/ mustn't /should/ come with us because she's broken her leg. 9. i didn't feel very well yesterday. i can't/ shouldn't /mightn't/ couldn't eat anything 10. you can't/mustn't/ should/might look at me when i am talking to you

1. jonathan may/might/ can/ should ski really well and he often wins his races
2. i can/must/ might/ought to go to the party but i'm still not sure
3. i think you should/ must/ shall/will go out more and meet new people
4. it's dangerous to go into deep water if you can't/ shouldn't/ mustn't/ mightn't swim
5. i can/ mustn't /might/ should go out later with my parents but i don't really know
6. all passengers must/mustn't/ might/ can't remain in their seats and must/mustn't/ might/can use their mobile phones
7. you can/ should/ must/ might wear a uniform when you're in the army
8. she can't /may/ mustn't /should/ come with us because she's broken her leg.
9. i didn't feel very well yesterday. i can't/ shouldn't /mightn't/ couldn't eat anything
10. you can't/mustn't/ should/might look at me when i am talking to you

1. can
2.ought to 
3. should
4. can't
5. might
6.  must/mustn't
7.  must/
8.  can't
9. couldn't 
10. should