A:银和水银
B:金刚石和石墨
C:铁粉和铁丝
D:冰和干冰
一Sorry, Charlie is not in. Can I take a(n) ?
一Thanks. Please tell him to call Andy back.
如图1是边长为1的六个小正方形组成的图形,它可以围成图2的正方体,则图1中小正方形顶点A,B围成的正方体上的距离是____