At the same time, their lives are on the line because one mistake in the darkness could be fatal.

他们在此同时也冒着生命危险，因为在黑暗当中，就连一个小错也能致命。

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Applying decorations to a flawed surface can be a costly mistake - and sometimes even a fatal one.

适用于装饰品的表面检测，表面裂纹对于装饰品来说是要付出昂贵的代价，有的时候甚至是致命的。

youdao

Made the fatal mistake of hitching entire franchise to one mega star, something small market teams in the NBA should never, ever do (has anyone heard from the Minnesota Timberwolves since Kevin Garnett bolted for Boston?).

FORBES: Net Impact Of LeBron's Decision On Team Values