机架类型为6U的M600设备识别机架的拨码开关位于（）
A、1#电源板对应的背板
B、NCP板
C、18#电源板对应的背板
D、电源板
参考答案：C
城域骨干网以基于DiffServ为主的QoS技术提供突发拥塞时的QoS保证。
Is it he or you________in charge of the job and supposed to complete it punctually?[ ]
A. who is
B. that is
C. who are
D. whom are
