A mother-in-law on a honeymoon is a fifth wheel.

度蜜月时，丈母娘是个大电灯泡。

I am tired of being treated like the fifth wheel around here.

我讨厌在这儿被当作多余的东西。

I'm tired of being treated like the fifth wheel around here .

在这儿工作，我感觉自己只是一个旋转不停的齿轮。

He was the only one without a date, so he felt like a fifth wheel.

他是唯一没被邀请的人，因此他感到自己很是多余。

The team already had two goalkeepers, so I felt like a fifth wheel.

队里已经有两个守门员了，我完全是多余。