1.There are a lot of tickets left, so you.....pay for the tickets in advance.
a.mustn't
b.won't
c.shouldn't
d.needn't
2.They.....a lot because they're very good musicians.
a.must have practiced
b.should have practiced
c.might have practiced
d.would have practiced
3.It's your own fault, you.....to bed so late.
a.can't have gone
b.shouldn't have gone
c.mustn't have gone
d.might not have gone