( )具有序列演替的特性。
A．主导产业 B．支柱产业 C．重点产业 D．基础产业
参考答案：A
Good technique in medicine means less pain and fewer deaths and, _____, it's our duty to master it. [ ]
A. naturally
B. therefore
C. particularly
D. similarly
甾体皂苷类的C17侧链为（）
A.羟甲基衍生物
B.不饱和内酯环
C.含氧螺杂环
D.脂肪烃
E.戊酸
