ADSL技术采用（）耦合在普通电话线上.
A.无源方式
B.有源方式
C.两者都不是
参考答案：A
— Are you sure Mr Bush is at home?
— Let's try ringing the _____. [ ]
A. apartment
B. bedroom
C. doorbell
D. building
什么是过渡配合？
