埋地排水用聚氯乙烯双壁波纹管，管道安装完毕检查合格后，做闭水检验时，向管道内充水并保持（）。 ["下游管内顶以上2m水头压力","上游管内顶以上2m水头压力","本管段管内2m以上水头压力","上游管外顶以上1m水头压力"]
下列指标中反映项目盈利能力的指标是（） ["财务净现值","财务内部收益率","投资利税率","投资利润率","资产负债率"]
GIS能够解决在发生洪水、战争、核事故等重大自然或人灾害时，如何安排最佳的人员撤离路线、并配备相应的运输和保障设施的问题，这是GIS在（）领域的应用。 ["基础设施管理","应急响应","资源管理","城市规划"]
Which cisco collaboration service will encourage true customer intimacy by quickly and proactively connecting people with the information, expertise and support that they need?（） [" ip communications"," conferencing"," customer care"," telepresence"," messaging"]
磨损过程大致可分为三个阶段：
断路器拒绝跳闸怎样查找处理？
