Question

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

Answer 1

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。