历史上修筑长城的高潮期为()。 ["秦","汉","唐","宋","明"]
使用火花间隙检测一串4片绝缘子的35kV设备时,零值绝缘子达到()片时,应立即停止检测。 ["1;","2;","3;","4。"]
带电水冲洗应遵守()顺序。 ["先冲上层,后冲下层,从上风侧开始自上而下的冲洗;","先冲下层,从上风侧开始自下而上的冲洗;","先冲下层,后冲上层,从下风侧开始自下而上的冲洗;","先冲上层,后冲下层,从下风侧开始自上而下的冲洗。"]
220kV线路带电作业中,绝缘绳最小有效长度为()m。 ["0.7;","1.0;","1.8;","3.7。"]
()是皇家专用的殿顶形式。 ["悬山顶","庑殿顶","歇山顶","攒尖顶","箓顶"]
怎样理解“安全第一”的含义?