[电] F级绝缘材料 class-f insulating material: f类绝缘材料class insulating material: 绝缘材料class-a insulating material: a类绝缘材料class-b insulating material: b类绝缘材料class-c insulating material: c类绝缘材料下载手机词典可随时随地查词查翻译