It' s a pity that there are many teenagers only on-line activity is chatting with their e -pals !
A. who
B. that
C. which
D. whose
网友回答
A. who
B. that
C. which
(答案→)D. whose
解析:句意:很遗憾,有很多青少年在网上的活动只是与网友聊天。通过分析句子结构,可知这个句子中包含一个主语从句和一个定语从句。横线之后到句末是一个定语从句,且关系词在定语从句中作定语,故用whose,选D。