软下疳由下列哪种病原体感染引起（）。
A.淋病奈瑟菌
B.人 * * 瘤病毒
C.杜克嗜血杆菌
D.梅毒螺旋体
E.沙眼衣原体
参考答案：C
In western culture,21 was the age________ young people traditionally received a key to their parents’ door, as a symbol of entering adulthood.
A．in which
B．on which
C．at which
D．to which
古代医学家把医学称之为（）
A.医术
B.人术
C.仁术
D.技术
