Since this attachment has two carbons, we call it an ethyl group.

由于这个连接有两个碳， 我们称之为乙基。

It has two branches, an ethyl group and a methyl group.

它有两个分支， 一个乙基和一个甲基。

So, if we number the chain the right way, the ethyl group will end up at position 4.

因此，如果我们以正确的方式对链进行编号， 乙基将位于第 4 位。

The structure we just used had a methyl group on it and an ethyl group on its fifth, it would be 5-ethyl-2-methyloctane.

我们刚刚使用的结构上有一个甲基， 第五个有一个乙基，它是 5-乙基-2-甲基辛烷。