分离水溶性生物碱时，多采用
A．乙醇沉淀法B．碘化铋钾沉淀法C．铅盐沉淀法D．雷氏盐沉淀法E．乙醚沉淀法
参考答案：D
A great many visitors come to visit the church ________ the 13th century, which has brought large income to the local government.
A．dated from
B．dating from
C．which was dated from
D．which dated from
孟塞尔表色法用类似（）的模型。
A、正方形
B、长方形
C、陀螺形
D、球形
