The traffic is moving very slowly as so many cars   on their way back to Shanghai.

A．am

B．is

C．are

D．be

某患者，乏力，进行性头晕，半年余，食欲不良，经常嗳气，贫血貌，无黄疸，肝脾不大，浅表淋巴结不大，无出血点，血常规为大细胞正色素贫血，骨髓象检查，粒、红、巨三系呈巨幼样变，本病最有可能的诊断是（）

A.巨幼红细胞贫血

B.急性白血病

C.缺铁性贫血

D.溶血性贫血

E.慢性病贫血