Although it seemed to be ______ painful experience, he still found it ______ fun. [ ]

A. a, /

B. /, a

C. a, the

D. a, a

一个底面直径和高都是3分米的圆锥，它的体积是______立方分米，一个与它等底等高的圆柱的体积比它大______立方分米．