They are one of the most important ways of protecting a house中为什么用are

They are one of the most important ways of protecting a house中为什么用are
They are one of the most important ways of protecting a house中为什么用are

They are one of the most important ways of protecting a house中为什么用are
主语是they,是复数,所以谓语动词用are、

因为是用的they，所以必须用复数are

they are 用错了，应该是it is

前面是they怎么不会用复数are呢，所以要改也要改成it is

前面是they，只能用are了

They是复数，所以应该用are。
这里这个they 合在一起成为最重要的方法中的其中之一，但是谓语are还是针对主语they 的。
希望能有帮助：）