Fifth wheel
01
自由轮, 转向轴承
a steering bearing that enables the front axle of a horse-drawn wagon to rotate
02
备用轮胎, 第五个轮子
an extra car wheel and tire for a four-wheel vehicle
03
第五个轮子, 多余的人
someone who is considered as an unneeded or unwanted person within a group of people
例子
I did n't realize that the party was for couples only, so when I showed up alone, I felt like a fifth wheel.
我没有意识到这个派对只限情侣参加，所以当我独自出现时，我感觉自己像个第五个轮子。
04
第五轮, 一种设计为由配备特殊挂钩的皮卡车牵引的露营车类型
a type of camper that is designed to be towed by a pickup truck equipped with a special hitch
例子
The fifth wheel offered all the comforts of home, including a full kitchen and bathroom, making long road trips enjoyable.
第五轮提供了家的所有舒适，包括完整的厨房和浴室，使长途公路旅行变得愉快。
