单项选择题
A.20mm*2mm B.30mm*3mm C.40mm*4mm D.50mm*5mm
A.40mm*4mm的镀锌扁钢 B.60mm*6mm的镀锌扁钢 C.不小于95mm2的多股铜导线 D.不小于35mm2的多股铜导线
A.18m B.20m C.22m D.24m