--What kind of makes 3G cellphones so popular with the young? --Video communication I t

问题补充：

--What kind of makes 3G cellphones so popular with the young?

--Video communication, I think.

A. mark

B. sign

C. symbol

D. feature

答案：

A. mark

B. sign

C. symbol

(答案→)D. feature

解析：考查词义辨析。mark标记，sign 符号，symbol 象征，feature特征，句意：哪种特征使3G手机在年轻人中如此的受欢迎。我认为是视频交流。所以选D。