选择有组织排水时,每根雨水管可排除大约()m2的屋面雨水,其间距控制在()m之内。
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挖掘机装载时,发现悬浮岩块或有塌陷征兆,应立即停止作业,并将设备开到安全区域。
A. 正确
B. 错误
The frequency of the alternating current generated by a synchronous generator is governed by the speed and the()
A. full excitation
B. load
C. power factor
D. number of pole