---Why does Tom’s mother ask him to drink milk?

---She says it’s         drink., and it’s good for his          .

A．health; healthy

B．healthy ;healthy

C．health; health

D．healthy; health

下列叙述正确的是 [ ]

A．原子晶体中可能存在离子键

B．分子晶体中不可能存在氢键

C．在晶体中可能只存在阳离子不存在阴离子

D．金属晶体导电是金属离子所致