It has been used to detect gold which has been buried in the ground.

问题描述:

It has been used to detect gold which has been buried in the ground.
请问gold前面为什么不加the
为什么ground前面有the
这俩个词在前文中都没有提到.
这是新概念英语2册5课原话.

gold 是泛指,不是特指,意思是任意的黄金都可以检测
in the ground 应该是固定搭配.