1岁时头围、身高是（）。

A.头围34cm；身高50cm

B.头围46cm；身高75cm

C.头围48cm；身高85cm

D.头围50cm；身高105cm

E.头围35cm；身高140cm

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

(21) 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.

(22) is a professional organization of individuals in multiple professions which focuses on effort on lower-layer protocols.

(23) functions with two layers of protocols. It can connect networks of different speeds and can be adapted to an environment as it expands.

(24) is the popular LAN developed under the direction of the IEEE802.5.

(25) 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.

（24）是（）

A. Ethernet

B. Token Bus

C. Token Ring

D. DQDB