问题
选择题
--- 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
答案：C
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。