In a public place there was an off-chance they might get caught.在公共场所, 他们被抓住的可能性极小。

He had taken a flight to Paris on the off-chance that he might be able to meet Francesca.他怀抱一丝希望坐飞机到巴黎, 心想或许能够遇到弗朗西丝卡。

an American visitor who had turned up on the off-chance of catching a glimpse of the princess为有幸一睹王妃风采而前来的美国游客

I came on the off-chance I'd see her.心想也许能有幸见到她, 我就来了。