The factory produces half a million pairs of shoes every year,80% are sold abroad.
A. of them
B. which of
C. of which
D. of that
网友回答
A. of them
B. which of
(答案→)C. of which
D. of that
解析：
试题分析:考查定语从句。由结构判断后面是非限制性定语从句，排除A、D选项，而B选项形式错误，故答案选C。句意：这家工厂每年生产五十万双鞋，其中80%都被销售到了国外。