【单选题】对 KIDDE 型干货舱烟雾探测系统电气控制线路原理理解正确的是 ______ 。 A. 当货舱火警发生时, N 电磁线圈失压,使相应的触点断开 B. 火警发生时,火警辅助继电器接通故障报警信号电路,保证火警的优先级 C. 有烟雾通过光电单元时,由于烟雾颗粒的折射作用,使光电池输出电压减小 D. 无烟雾通过光电单元时,光电池输出电压很小
【单选题】The Mayan Indians lived in Mexico for thousands of years before the Spanish arrived in the 1500s. The Maya were an intelligent, culturally rich people whose achievements were many. The Mayan people kn...