a fifth wheel
常见例句
- A car does not need a fifth wheel.
一輛車通常不需要第五衹輪子。 - By definition, a fifth wheel is a wheel or a portion of a wheel with two parts rotating on each other that sits on the front axle of a carriage and adds extra support so it doesn’t tip.
通過定義，第五個輪子，是成爲一個四輪馬車的前車軸上互相鏇轉的兩個部分的一個輪子或一個輪子的一部分，而加上一個額外的輔助輪子，這樣它就不會傾斜。 - He was the only one without a date, so he felt like a fifth wheel.
他是唯一沒被邀請的人，因此他感到自己很是多餘。 - Trailers are typically attached to tractors by a "fifth wheel, " in which a coupling pin on the trailer fits into the center of a large horseshoe-shaped piece of metal.
NPR: Runaway Trailer Crashes Rare; NY Accident Killed 7 返回 a fifth wheel