I/2-a
3-c (pour moi, je dirais 'a')
4-c (pour moi, je dirais 'a')
5-a
6-c (absence d'obligation)
7-a
8-b
9-c (absence d'obligation)
10-a
11-a
12-a
13-a
14-c (pour moi, je dirais 'a')
II/1-must
2-can
3-can
4-may
5-must
6-can
7-may
8-may
9-must
10-must
III/1-My shopping bag is heavy, but I will be able to carry it.
2-Will I be permitted to smoke when the ladies arrive?
3-They will have to buy a newspaper to know the truth.
4-It's possible my sister will come with us, but I'm not sure she will.
5-They will probably feel terribly sad after their mother's death.
IV/1-may
2-may