I wrote ______ article on the educational visit to Canada for the school newspaper last night. [ ]

A. the

B. an

C. a

D. /

正常滑膜液中可见下列细胞，但除外的是（）。

A．红细胞

B．单核—巨噬细胞

C．淋巴细胞

D．中性粒细胞

E．软骨细胞