● (74) functions with two layers of protocols.It can connect networks of differe
● (74) functions with two layers of protocols．It can connect networks of different speeds and can be adapted to an environment as it expands．
(74) A．The hub
B．The bridge
C．The router
D．The proxy
正确答案：B【解析】译文：网桥涉及了两层网络协议，它能连接不同速度的网络。作为扩展，还可以改变以使用某个环境。
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