They set up a plant _ produced things _ had never been seen before.
问题描述：
They set up a plant _ produced things _ had never been seen before.
A.where,which B.which,that C.where,that D.that,where
答
B为什么因为两个空白处的关系词都是在从句中做了主语，只有关系代词才可以胜任，故反身有关系副词where的那三个都被轻易地排除了。