题目

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   考查定语从句，先行词是Gun control，指物，关系词在从句中做介词的宾语，介词前置，介词与从句动词构成搭配argue about sth.，选C。  

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