—Jack, _____ you behave yourself? You're no longer a kid．—Sorry, Daddy．It won't happen again．

I want to open the door, but it _____ open.

—Must I buy lunch at school?—No, you needn’t. You __________ bring your own lunch if you want to.

 — _________ I use your telephone?— Yes, of course.

He____know the answer, but I’m not sure.