The factory produces two million pairs of shoes every year, half ______ are sold abroad.

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

答案及解析： A

解析：

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。