诊断急性坏死性龈炎时主要根据临床特征，但也有辅助诊断方法，其方法是

A．活体组织检查

B．脱落细胞检查

C．坏死物及牙龈组织培养

D．坏死物涂片、革兰染色

E．细菌药物敏感实验

—Mr. Green has _____ one-year-old son, doesn’t he?

—Yes, and he also has _____ 8-year-old daughter.[ ]

A. a; a          

B. an; a            

C. a; an          

D. an; an