下列哪些氟化物不用于含氟牙膏
A．氟化亚锡
B．氟化钠
C．氟化铵
D．单氟磷酸钠
E．氟化钾
参考答案：E
—Mum, is the pair of gloves mine?
—Yes. You have to wear another pair.
A．washing
B．have washed
C．having washed
D．being washed
校本培训的主要目标是什么？
