单项选择题
A.有操作禁止送电 B.要害部位闲人免进 C.谢绝参观 D.勿打扰
A.9m/s B.12m/s C.15m/s
A.0.5m B.1.2m C.1.5m D.1.8m
A.20% B.30% C.50%
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