— Peter, you are in the new school for two weeks. How are you getting on with your classmates?      

— ______. [ ]

A. Very well

B. Well done

C. That's OK

D. I'm fine

对中性粒细胞具有趋化作用的物质是()

A．C3a

B．C5a

C．细菌代谢产物

D．坏死组织

E．阳离子蛋白