protective gas保护气体protectiveadj.保护的；防卫的protective blinking reflexes防御瞬目反射protective card of hard disk硬盘保护卡Protective System of Witness证人保护制度Protective index of farmland耕地保有指标protective relay test device继电保护测试仪protective oral-nasal mask防毒口罩Protective Shielding Program保护性屏蔽计划Protective metal sump shield发动机底盘保护钢板protective bonding conductor保护连接导体protective multiple earthing保护性多点接地