Какой модальный глагол нужно подставить в следующие предложения?

1.сan
2.should
3.should
4.can
5.must

1. You have to/must/should/ought to go and see it yourself.
2. Nobody is allowed to/may/ should enter my room without permissian.
3. Why should I/do I have to believe this stranger?
4. Could/would/will/can you please help me to open this door?
5. I'm sorry, but I must/have to leave you now.