He found themat a tablechess.A. sat to play B. sitting playing theC. seated playingD. s

问题补充：

He found themat a tablechess.

A. sat, to play

B. sitting, playing the

C. seated, playing

D. seat, play the

答案：

A. sat, to play

B. sitting, playing the

(答案→)C. seated, playing

D. seat, play the

解析：考查非谓语动词。句意：他发现他们正坐在一张桌子旁下棋呢。表示“坐着”的状态，用seated或sitting，find sb doing/done发现某人怎么样；排除A、D；棋类和球类前不加the；play chess下棋，故选C。