先天性主动脉瓣异常可分为四种畸形，下列哪项是错误的
A.单瓣
B.二瓣
C.三瓣
D.四瓣
E.六瓣
参考答案：E
This is my . [ ]
A. families
B. family
C. the family
选用治疗急性坏死溃疡性牙龈炎最敏感的抑菌药物是( )
A．四环素B．金霉素C．磺胺类D．甲硝唑E．青霉素
