—Can we leave the classroom now?
—No, you _________. You _________ to leave until the bell rings.

A．don’t have to; are supposed	B．mustn’t; are allowed
C．needn’t; aren’t allowed	D．can’t; aren’t supposed

科目 英语   题型 单选题   难度 中等

知识点： 情态动词的被动语态