问题
选择题
(2009·陕西)Gun control is a subject ________ Americans have argued for a long time.
A．of which
B．with which
C．about which
D．into which
答案
答案：C
先行词为subject，将先行词还原到定语从句中：Americans have argued about the subject for a long time。由此可以看出被还原部分为about the subject，这样可以确定所选的介词为about。