All the beepers and mobile phones must ___ in class

问题描述:

All the beepers and mobile phones must ___ in class
A.keep off B.take off C.be taken off D.be kept off

D.be kept off
这里是被动语态
在教室里,所有的传呼机和手机都必须被关闭(保持关闭状态).
中文里可以省略 被
但是英语中要将被动语态表现出来