leave: vt

the furniture inside: 宾语，inside为后置定语

exactly where it was：宾语补足语从句，exactly修饰where

还可以为：leave the furniture as it was. 同样的结构。

参考下面几个句子：

The book is where it should be. where引导表语从句。

Put the book where it should be. where引导地点状语从句。

Leave the book where it is. where引导宾语补足语从句。