下列地图的图幅大小相同，图中表示的内容最详细的是[ ]

A、世界地图

B、中国地图

C、北京市地图

D、京津塘地区图

—Excuse me , Have you got an eraser?

—Sorry, I haven't.  Why _____ you ask Mary? Perhaps she has one.[ ]

A.  do    

B.  don't  

C.  did    

D.  didn't