A:铜锌原电池中铜是正极
B:铁壳船底部镶嵌铜块,铜块更易被腐蚀
C:用电解法精炼粗铜时粗铜作阳极
D:在镀件上镀铜是可用金属铜作阳极
His erasers are in his ____ (mother) bag.