论述钢板弹簧与减震器的作用?
光伏发电站并网点频率在()范围内应能连续运行。 ["49.0Hz~51.0Hz","49.3Hz~50.2Hz","49.5Hz~50.2Hz","49.7Hz~50.2Hz"]
钢筋混凝土结构中钢筋作用是承受()。 ["压力或拉力","容许应力","强度","极限强度"]
并网点电压在高于120%额定低于130%额定时,光伏发电站应至少持续运行()s。 ["0.1","0.5","1","10"]
冬季施工混凝土如单从温度方面考虑最好采用哪种运输机械()。 ["手推车","输送泵","输送带","翻斗车"]
简述发射掉信号。