分离秦皮甲素和秦皮乙素可选用的方法有()
A.水蒸气蒸馏法
B.碱溶酸沉法
C.系统溶剂提取法
D.硅胶柱层析法
E.水提醇沉法
参考答案:A, B, C, D
There was __________rain last night and it’s _________cold now.
A.too many; much too
B. much too; too many
C.too much; much too
D.much too; too much
道德既是人们的行为准则,又是评价人们思想和行为的标准。( )