— Hello, I ____ to ask if I can book two tickets for tonight's film.

— Sorry, we've already sold out.[ ]

A. phone

B. will phone

C. am phoning

D. have phoned

早产儿比同龄足月儿更易发生缺铁性贫血的主要原因是（）

A.生理性溶血释放铁较少

B.食物中铁利用率较低

C.生长发育快及先天储铁少

D.红细胞寿命短

E.铁排泄量多