—What's wrong with your coat?

—Just now when I wanted to get off the bus, the man next to me _________ on it. [ ]

A. is sitting

B. had sat

C. sits

D. was sitting

综合布线采用（）和相关连接硬件，模块化设计，因此所有通道都是通用的。

A．专用通道

B．标准光纤

C．标准的传输线缆

D．双绞线