Some people here said they had ________ a boy in blue near the stop. But where can he be?

A.found; to play

B.seen; play

C.found; playing

D.seen; playing

答案及解析： B

解析：

根据后文可知，这个孩子还未找到，所以不论found还是seen后都不能跟现在分词，句意应为“发现”或“看见”“在车站附近玩过”，而没有“find sb. to do sth.”结构，故选B。