曹老师讲得可能比较抽象一些。我给网友解释这个句子的缘由：

Becasue there was nothing to do, we went home.

上句应该很好懂。这是个主从句，表达因果关系。

一、 在书面语中，为了让表达富有变化，我们把一个次要的从句成分，用非谓语表示。现在，我们把原因状语从句用现在分词表示：存在句 There be 中 的 be， 也有“现在分词形式” being，因此，把 There was nothing to do  变成了  There being nothing to do。改变之后，就成了一个简单句。

There being nothing to do, we went home.

二、 网友说直接用 Nothing to do,we went home. 也是可以的，显得更加简练。它是 With nothing to do 的变式。

三、 同样的意思，可以有灵活多样的表达。以下说法均可选择：

1. Becasue there was nothing to do, we went home.

2. There was nothing to do, so we went home.

3. There was nothing to do, and we went home.

4. There being nothing to do, we went home.

5. With nothing to do, we went home.

6. Nothing to do, we went home. （尤为口语）