防爆电气设备的标志包含型式、等级、类别和组别 , 应设置再设备外部主体部分的明显地方,且应在设备安装后能 清楚看到。标志“ Er d ⅢB T3 Gb的正确含义是( ) 。
A、增安型“d”,防护等级为Gb,用于T3类IIB组的爆炸性气体环境的防爆电气设备C
暂无解析
Thecentraltheatrehasaseating________ofmorethan3,000people.
Ifhe_____thestorekeeper‘sscissors,hewouldhaveforgottentobuyapair.
Iftheoperation________carefullyprepared,itwouldnothavebeensuccessful.
Themeeting_____nextweekwillbeofgreatimportance.
熟悉各种传染病潜伏期最重要的意义是()