Will you   __     the light? It's dark in the room. I can't see clearly.[ ]

A. turn on    

B. turn of    

C. turn down    

D. turn up

桡骨： ()

A．上端大，下端小

B．下端的下面与第一掌骨底相关节

C．桡骨头的周缘有环状关节面

D．下端的内侧面称桡切迹