Coin collection is interesting, but you find a valuable coin only once in.

收藏钱币很有趣，只是难得有一次找到一个有价值的。

youdao

Coin collecting is interesting, but you find a real valuable coin only once in a blue moon.

硬币收藏很有趣，不过得到一个真正有价值的货币几乎是不可能的。

youdao

All the shillings disappeared and the only coin left was the guinea.

所有的先令都消失了，只剩下几尼。

youdao

In the case of the coin toss, there are only two, but I'm saying in general there could be an infinite number.

在抛硬币的例子里,只有两个取值,但是一般都会有无限个可能值

耶鲁公开课 - 金融市场课程节选

So all the shillings disappeared and the only coin left was the guinea.

所以，所有的先令就消失了,只剩下几尼作为唯一的硬币。

耶鲁公开课 - 金融市场课程节选

If we delay the transition to only a coin dollar, the problem may well solve itself.

FORBES: GAO Proposed Ditching Dollar Bill in Favor of Coin

The price Joyce paid was not only in the coin of professional tribulation.

NEWYORKER: Silence, Exile, Punning

Instead of each denomination containing precious metal, only one higher-denomination coin would do so.

ECONOMIST: The lessons of sound money from 1,000 years' experience