—Have you written anything on Chinese traditional food so far?

—_____, but I have a plan for it. [ ]

A. Ever since

B. Later on

C. Not yet

D. From  now on

某医院151例慢性胃炎患者的住院时间见表。欲求其住院时间的平均水平，应选择（）。

A.中位数

B.平均数

C.相对数

D.均数

E.几何均数