by some chance

基本解释

Unless, by some chance, they believe in Magic.
除非，鬼使神差让他们相信了魔术师的话。
By some chance the little table at which I sat had escaped the eye of incomers, and two vacant chairs at it extended their arms with venal hospitality to the influx of patrons.
不知何故，我所坐的桌子不为人关注，还有两把空着的椅子张开双臂，以诱人的殷勤迎接着涌入的客流。
And, if by some chance you don't, you'll have a great life anyway.
即使由于某些原因你没能去成，你的生活依然是丰富多彩的。
372180600.qzone.qq.com

More precisely you could promise the following: If by some chance this economy starts to take off and desired savings falls below desired investment then I will raise interest rates so far, so fast that it will crush every single investor in America, drive homebuilders into a ditch, shutter factories, skyrocket the Federal debt and put half the population on the bread line.
FORBES: How To Keep Zero Interest Rates Forever
By chance, they had spent some years of life together—that was all.
NEWYORKER: Town of Cats
The fiscal cliff package actually might have had some chance of diminishing deficits by raising taxes on the middle class, the only group big enough to materially affect tax revenues.
FORBES: The Republican Fiscal Cave Is Much Worse Than The Fiscal Cliff