（）是石油化工行业应用最为广泛的灭火系统，主要用于扑救可燃液体火灾，也可用于扑救固体物质火灾。 ["气体灭火系统","泡沫灭火系统","细水雾灭火系统","水喷雾灭火系统"]
风湿性关节炎较常见的关节外表现是（） ["胸膜炎","贫血","血管炎","类风湿结节"]
简述同向异频简谐振动在不同频率和不同幅值下合成的特点。
Which two of these are correct regarding the recommended practice for distribution layer design based on the following configuration?（） [" use a Layer 2 link between distribution switches"," use a Layer 3 link between distribution switches"," use a redundant link to the core"," use a Layer 3 link between distribution switches with route summarizatio"]
电力管理部门应将经批准的电力设施新建、改建或扩建的规划和计划通知（），并划定保护区域。 ["安全部门","劳动部门","城乡建设规划主管部门","施工部门"]
简述质性研究的资料分析步骤。
