单项选择题

广域网覆盖的地理范围从几十千米到几千千米，它的通信子网主要使用（）。

A．报文交换
B．分组交换
C．文件交换
D．电路交换

你可能感兴趣的试题

单项选择题

The author does not think that a simple "Thank you" really matters.
A、正确
B、错误

多项选择题

According to the video, what are the ways to protect our environment?
A、We should save the paper， the water， the food and so on.
B、We should protect the trees
C、No littering.