然而，一次偶然的机会下，男孩们打了起来，水壶也掉进了井里。

Once there, though, the boys began to fight and the water jug fell into the well.

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但是一次偶然的机会，他发现已故祖父家有一个破旧但功能齐全的实验室，正是这个发现使得这位年轻人确定了他对化学的热情。

But it was a chance stumbling upon a run-down, yet functional, laboratory in his late grandfather's home that solidified the young man's enthusiasm for chemistry.

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生物物种总是会利用偶然的机会或者是适宜的环境四处散布。

Species have always moved around, taking advantage of happenstance or favorable circumstances.

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