[问答题] 简述自动喷水灭火系统中水力警铃和压力开关的主要作用。

中高及以上风险产品销售起点不低于（）万元。 ["5","10","15","20"] The present voyage of my ship began at the port of Shanghai after loading 8 000 tons of Cargo on board and ended after discharging the Cargo at the port of Hong Kong，which was（）. ["the port of destination","the next port of call","the port of arrival","the last port of call"] 依据华电集团《电力安全生产工作规定》，一般事故隐患是如何定义的？ 对PDC主机和基础结构主机，除可以使用命令行外，还可以用（）。 ["AD用户和计算机","AD域和信任关系","计算机管理","控制台"] 依据华电集团《电力安全生产工作规定》，电力生产类企业是指什么企业？ 简述自动喷水灭火系统中水力警铃和压力开关的主要作用。