Helen got into acting purely by accident.

海伦当演员完全出于偶然。

《牛津词典》

She discovered the problem by accident during a visit to a nearby school.

她在去附近一所学校参观时偶然发现了这个问题。

《柯林斯英汉双解大词典》

It happened—whether by accident or design —that the two of them were left alone after all the others had gone.

碰巧—不知是偶然还是有意安排—其他人走后，只剩下了他们两个人。

《牛津词典》

Still,many people argue that his talent should be recognized because ten national coaching victories do not happen by accident.

VOA: special.2009.07.10

In fact, you'll find the probability of this happening 3% is only about 3 percent, of it happening just by accident.

实际上你会发现,出现这种情况的概率是，所以说他们的实验结果完全是偶然的。

麻省理工公开课 - 计算机科学及编程导论课程节选

And in the process of tidying it up and making it prettier, I'll often by accident find the bug.

让我的程序更漂亮些,在这个清理美化代码的过程中，我常常无意中发现我的错误。

麻省理工公开课 - 计算机科学及编程导论课程节选

His family say he is innocent and strayed across the border in Punjab by accident.

BBC: India plea to Pakistan over beaten Sarabjit Singh

His family say he is innocent and merely strayed across the border in Punjab by accident.

BBC: India anger over Sarabjit Singh attack in Pakistan jail

No, no, that man who has stopped near the Coliseum is there purely by accident.

NEWYORKER: So It Is in Life