In order to catch up with her classmates, _____.

A．a lot of books were bought by Mary’s mother

B．Mary’s father helped her with her lessons

C．Mary worked hard at her lessons around the clock

D．Mary’s classmates helped her a lot

男性，56岁。患慢性骨髓炎8个月，血红蛋白70g/L，白细胞、血小板正常。血清铁6.21μmol/L，铁蛋白206μg/L，骨髓增生活跃，细胞外铁（+++）。

该病的发病机制描述不正确的是（）

A.红细胞干细胞凋亡过早

B.红细胞生成素相对不足

C.机体造血储备能力降低

D.单核巨噬细胞释放内铁障碍

E.细胞利用铁障碍