形成肝纤维化的主要细胞是()

A．肝细胞

B．胆管细胞

C．肝星状细胞

D．血管内皮细胞

E．中性粒细胞

—Why don't you answer my question, Bill?

—              difficult for me to answer. [ ]

A. Too

B. So

C. Such

D. Very