氟化钠溶液每日含漱一次的浓度为
A．2.0%B．0.2%C．0.5%D．1.0%E．0.05%
参考答案：E
试述维生素D缺乏性佝偻病的发病机制。
All the imported goods should comply ( ) the requirements of CIQ.
A．with B．from C．by D．for
