单项选择题
A.过压 B.欠压 C.短路 D.过载
A.0.5m B.1m C.0.7m D.1.5m
A.铜线1mm2,铝线2mm2 B.铜线5mm2,铝线5mm2 C.铜线1.5mm2,铝线2.5mm2 D.铜线10mm2,铝线20mm2