Gun control is a subject Americans have argued for a long time.
A. of which
B. with which
C. about which
D. into which
网友回答
A. of which
B. with which
(答案→)C. about which
D. into which
解析：考查定语从句，先行词subject,定语从句中argue后面缺少 (with sb. )about/over sth
，所以用about which 来引导定语从句。句意为：枪支控制是一个美国人争论了很久的问题。选C。