I think the teacher must( )carefully in class first.

问题描述:

I think the teacher must( )carefully in class first.
A.listen B.be listened C.be listened to D.be listening

C.
be listened to被听.因为是学生听讲不是老师认真听所以不能选A(虽然语法过得去).
be+动词 是被动结构.
望采纳.谢谢.