村民王大伯投资修建两个正方形养鱼池，已知大鱼池的面积比小鱼池面积大2000平方米，两个鱼池的周长之和为400米，求两个鱼池的边长．

Shen Xue and Zhao Hongbo won the gold medal for China so we're proud _____ them. [ ]

A. in

B. on

C. of

D. for