问题
选择题
The factory produces two million pairs of shoes every year, half _______ are sold abroad.
A．of which
B．which of
C．of them
D．of that
答案
答案：A
本题考查定语从句。“逗号”不能连接两个句子，所以所选之词应是连词，排除C项；that不能引导非限制性定语从句，排除D；介词应用在of前。