问题
单项选择题
Communication networks can be classified in terms of their physical arrangement or (74) . Three common (74) are the star, bus, and ring.
A. structures
B. topologies
C. protocols
D. frames
答案
参考答案：B
解析： 信息网络可以依据物理结构或拓扑结构进行分类，3个典型的拓扑结构是星形、总线型和环形。