What are two characteristics of the DiffServ model？（） ["service guarantee","traffic that is divided into classes","not scalable to large implementations","QoS mechanisms that are used without prior signaling","applications that signal their particular QoS and bandwidth requirement"]
列举世界上最早出现的定期报刊、日报和杂志。
阐述弥漫性血管内凝血（DIC）的临床诊断标准。
卫生法律责任（） ["属于行政责任","属于民事责任","属于刑事责任","包括行政责任、民事责任和刑事责任","一般都是行政责任和民事责任，没有刑事责任"]
工厂供电系统设计的技术指标和经济指标是什么？
层理
