变电硐室长度超过6m时，必须在硐室的（）各设1个出口。
A、一侧
B、对面
C、上下
D、两端
参考答案：D
B-ISDN的业务分成( )两类
A．交互型业务和会话型业务
B．消息型业务和检索型业务
C．交互型业务和发布型业务
D．检索型业务和发布型业务
The price of meat has increased greatly recently. In my opinion, it should remain ______, or people
will not be able to afford it. [ ]
A. valid
B. dynamic
C. stable
D. initial
