Unfortunately, due to unforeseen circumstances, this year's show has been cancelled.

遗憾的是，由于意外情况，今年的演出已被取消了。

《柯林斯英汉双解大词典》

The project was running late owing to unforeseen circumstances.

这个项目因意外情况而拖延了。

《牛津词典》

When arranging our work, we should allow for unforeseen circumstances.

我们安排工作时要留有余地。

《新英汉大辞典》

Then, add time and a half to account for unforeseen circumstances on the actual day.

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Despite the grandstanding, their views about raising taxes are the same: only in unforeseen circumstances.

ECONOMIST: The Democratic race: Nasty isn’t nice | The

This common law concept relieves a party from fulfilling a contract if unforeseen circumstances make it impossible to do so.

FORBES: Collateral Damage