The factory produces half a million pairs of shoes every year, 80% are sold abroad.
A. of which
B. which of
C. of them
D. of that
网友回答
(答案→)A. of which
B. which of
C. of them
D. of that
解析：此题考查定语从句。由于两句话之间无连词，所以只能构成定语从句；非限制性定语从句要用which指代物。