For each blank, choose the best answer from the four choices and write down on the answer sheet.

（）is a channel’s capacity which directly reflects the data transfer rate of the channel.

（）functions in a NetWare network which is used to define addressing schemes.

（）is a network layer device that supports multiple LAN interfaces and segments LANs into smaller collision and broadcast domains.

（）is the popular LAN developed under the direction of the IEEE802.3.

（）is a device which enables digital microcomputers to communicate across analog telephone lines.

（）functions in a NetWare network which is used to define addressing schemes.

A． NetBEUI

B． IP

C．IPX

D．NCP

原发性痛经的主要机理是

A．促性腺激素升高

B．前列腺素升高

C．雄激素升高

D．孕激素升高

E．雌激素升高