单选
For each blank, choose the best answer from the four choices and write down on the answer sheet.
(71)is a channel' s capacity which directly reflects the data transfer rate of the channel.
(72)functions in a NetWare network which is used to define addressing schemes.
(73)is a network layer device that supports multiple LAN interfaces and segments LANs into smaller collision and broadcast domains.
(74)is the popular LAN developed under the direction of the IEEE802.3.
(75)is a device which enables digital microcomputers to communicate across analog telephone lines.