Question

That art center is _______ used to be a factory, ______ mill

Answer 1

A

考查名词性从句及定语从句。第一空是表语从句，从句中缺少主语应用what，第二空为定语从句，先行词为a factory，从句中缺少地点状语，故用关系副词where，所以选A。