青霉素G钾制成粉针剂的目的是()
A.降低介电常数使注射液稳定
B.防止药物水解
C.防止药物氧化
D.降低离子强度使药物稳定
E.防止药物聚合
参考答案:B
_____ quite recently, most mothers in Britain did not take paid work outside the home.
A.Before
B.Until
C.From
D.Since
三方晶系和六方晶系具有相同的()。