Is this the factory( )we visited yesterday?

Is this factory( that)we visited yesterday?（这个工厂是我们昨天参观过的那个工厂吗?）Is this( the factory which/that)we visited yesterday?（这是我们昨天参观过的那个工厂吗?）两句话主语不同,分别为this factory和this你可以把它还原为陈述句就明白了啊：第一句变为：This factory is where we visited yesterday。第二句则是：This is the factory which/that we visited yesterday。