问题
选择题
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
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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：C
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4Fe2++Y+……，据此可知Y为( ) 