For each blank, choose the best answer from the four choices and write down on the answer sheet.
(66) is a six bytes OSI layer 2 address which is burned into every networking device that provides its unique identity for point to point communication.
(67) is a professional organization of individuals in multiple professions which focuses on effort on lower-layer protocols.
(68) functions with two layers of protocols. It can connect networks of different speeds and can be adapted to an environment as it expands.
(69) is the popular LAN developed under the direction of the IEEE 802.5.
(70) is the popular backbone technology for transmitting information at high speed with a high level of fault tolerance which is developed under the direction of ANSI.

A．Ethernet

B．Token Bus

C．Token Ring

D．DQDB

企业之所以出现，正是因为企业在某种状态下，可将外部的市场交易行为变成企业内部（）的合作和交换行为，组织管理费用低于市场的交易费用。

A.有交易

B.有组织

C.有计划

D.有监督

E.有奖惩