某弱酸性药物在pH=7.0的溶液中90%解离，其pKa约为（）
A.6
B.5
C.7
D.8
E.9
参考答案：A
按（）分类，我国政府行政机构可分为省（部）级机构、地（厅）级机构、县（处）级机构和乡科级等。
A.行政区划的层级
B.政府机构的行政级别
C.行政机构的常设与非常设
D.属性
--- Have we ______ water?
--- Yes, _____. We’d better get some.
A．run out of; we have run it out
B．run out of; our water has run out
C．run out of; our water has been run out
D．run out; our water has been run out.
