在薄层鉴别中，鉴别氨基酸成分常用
A．硅胶G板B．聚酰胺板C．纤维素板D．氧化铝板E．纸层析
参考答案：C
- Why does the lake smell terrible?
- Because large quantities of water ________ . [ ]
A. have polluted
B. is being polluted
C. has been polluted
D. have been polluted
女，15岁，身高125cm，无第二性征发育，有颈蹼及肘外翻，最有诊断价值的检查是
A．骨龄B．生长激素C．E2(雌二醇)D．染色体E．LH、FSH(促黄体激素和促卵泡生成激素)
