请问老师,下面的表示地点的介词短语是倒装句吗?如果真正的主语是a large store of chemicals,但是又为什么用谓语was呢?separated by a
semi-fireproof partition是分词短语修饰the burning building吗?
In the rear of the burning building, separated by a semi-fireproof partition, was a large store of chemicals owned by the JR Company, who formerly occupied the entire structure.