- Are you worried when your son often plays computer games? Yes. I think playing to

问题补充：

--- Are you worried when your son often plays computer games?

--- Yes. I think playing too many computer games on teenagers.

A. have a good effect

B. has a good effect

C. has a bad effect

D. have a bad effect

答案：

A. have a good effect

B. has a good effect

(答案→)C. has a bad effect

D. have a bad effect

解析：根据题意我对玩电脑游戏对孩子产生影响是担心的，玩太多的游戏对青少年有害，

故不选AB，玩电脑游戏是单数第三人称，故用has，故选C。