there is an ancient invention still used in some parts of the world today that allow people to seethrough wall.what is it?

there is an ancient invention still used in some parts of the world today that allow people to see
through wall.what is it?

有一项古老的发明,今天仍在世界上一些地方被使用.这项发明是允许人们看穿墙壁.它是什么?
有吗?窗啊?哈哈

答案：window
是题目没看懂吧？