小对话：

A: You come back so earlly. The party is boring? 你回来的这么早。舞会没意思?

B: All the boys and girls were dancing at the party while I sat at a table alone, feeling like a fifth wheel. 晚会上，所有的男孩和女孩都在跳舞，只有我孤零零地坐在桌边，感觉自己仿佛是一个多余的人。

虽然现在很多机车，特别是越野车的后面也会备上一个备用轮胎，但它们称之为spare wheel,或者spare tyre. 而不能称为the fifth wheel.

更多例句：

The chair is a fifth wheel, please take it away. 这把椅子是多余的，请把它搬走。

A mother-in-law on a honeymoon is a fifth wheel. 度蜜月时，丈母娘是个大电灯泡。

We decided to fire that worker, he was just a fifth wheel. 我们决定开除那个工人，他不过是个多余无用之人。

My son asked me to come help at his school track meet I felt fifth wheel when I got there: they already had enough people to help so I stood there feeling useless. 我的儿子要我在他学校开运动会的时候去帮忙。可是，我到了那里觉得自己似乎是多余的，他们已经有好多人在帮忙，我只好站在那里没事干。”

有关the fifth wheel的用法我们暂时了解到这里，记得一定要和spare wheel进行区别。它们分别表示“无用的;局外人”和“备用轮胎”。