Помогите пожалуйста! Сомневаюсь в этих вопросах.1. I was so tired. I ___ sleep

Помогите пожалуйста! Сомневаюсь в этих вопросах.
1. I was so tired. I ___ sleep for a week.
a)could
b) can
c)must
d)might
2. I have not phoned Ann for ages. I ___ phone her tonight.
a)could
b)can
c)must
d)have
3. If I ___my exams, my mother___me go to a disco
a) don't pass, won't let
b)won't pass,won't let
c) won't pass, let
d) won't pass, doesn't let
Заранее, спасибо!