第7题: [单项选择]Communication networks can be classified in terms of their physical arrangement or (73) Three common (73) are the star, bus, and ring. A. structures B. topologies C. protocols D. frames 参考答案:B 答案解析:[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型、总线型和环形。