When the students were playing games on the playground Jim suddenly stopped and began to

问题补充：

When the students were playing games on the playground, Jim suddenly stopped and began to cry, so we stopped what was wrong with him.

A. to play; seeing

B. playing; to see

C. playing; seeing

D. to play; to see

答案：

A. to play; seeing

(答案→)B. playing; to see

C. playing; seeing

D. to play; to see

解析：句意：当学生们在操场上玩游戏的时候，吉姆突然停止玩游戏，哭起来了，所以我们停下来，看看他发生了什么事。stop to do停止手中的事去做另一件事。stop doing停止正在做的事情。故选B。