（）是指分布数列中总体各单位标志值按大小顺序排列，处在中间位置的标志值。

A.算术平均数

B.中位数

C.众数

D.平均数

— We've only got this small bookcase. Will that do?    

— No, _    _ I am looking for is something much bigger and stronger. [ ]

A. who                  

B. that          

C. what            

D. which