a blessing in disguise

释义：“因祸得福”，尽管事情原本上看起来是一件不幸的事，但是从中能获取意想不到的利益，常用在描写失败和挫折的留学文书中以生动的体现自己得到了教益。

例句：
Two days later the doctors were saying the pneumonia was a blessing in disguise. Because of it, they'd found an undiagnosed heart problem.
The Y2K disaster could be a blessing in disguise for getting people on their bikes.