My father          to Nanning many times, so he knows it well.

A．went

B．will go

C．has gone

D．has been

下述哪种物质与吞噬细胞对细菌的杀伤降解无直接关系

A．阳离子蛋白

B．乳铁蛋白

C．髓过氧化物酶

D．调理素