That art center is used to be a factory, millions of tractors were produced.
A. where; where
B. what; where
C. what; which
D. where; which
网友回答
A. where; where
(答案→)B. what; where
C. what; which
D. where; which
解析：第一空的连词在表语从句中作主语，故选what；第二空后面连接的是定语从句，它是被动语态，所以不缺主语和宾语，故选where， 所以应选B。