Entering the room, I found Mary ______at the desk and ______a letter.

A．Seated；wrote

B．Sitting；written

C．Seating；writing

D．Seated；writing

下列哪个指标是反映医疗服务需要的指标

A.两周患者未就诊率 

B.两周患病率 

C.每千人口拥有医生数 

D.产前检查覆盖率 

E.人均住院天数