by accident 偶然;意外地
You do something by accident when you do it unexpectedly.
【例句】
I found the answer to the question by accident. 我偶然发现了那道问题的答案。
We met again, by accident, at the gym. 我们在体育馆偶然又碰到了。
【问题】
请翻译句子:我偶然发现了你的错误。
答案:I found your mistake by accident.