下列电信设备中，所产生成本属于通信流量敏感成本的是（）。

A.固定网络中的用户线

B.交换节点设备

C.大容量传输线路

D.终端设备

She's having a lot of trouble with the new computer, but she doesn't know whom to ______.[ ]

A. turn to   

B. look for  

C. deal with  

D. talk about