—_       did he come?

—He came to ask for help.

A．How

B．When

C．Where

D．Why

早期缺铁性贫血形态学改变为

A．小细胞正色素性贫血
B．小细胞低色素性贫血
C．正细胞正色素性贫血
D．大细胞性贫血
E．以上全不是