A:K+、Na+、HCO、NO
B:Na+、SO、Cl—、ClO—
C:H+、Mg2+、SO、NO
D:Ag+、K+、NO、Na+
常用氯气给自来水消毒,某学生用自来水配制下列物质的溶液,不会产生明显药品变质的是()
The boy is too young and he needs his mother____ (dress) him.
下列人口流动属于人口迁移的是( )