every cloud has a silver lining 黑暗中总有一线光明；守得云开见月明；天无绝人之路；否极泰来；乌云背后有阳光

【例句】
Optimists might say that every cloud has a silver lining.
乐观主义者可能会说，守得云开见日月。

As they say, every cloud has a silver lining. We have drawn lessons from the decisions taken.
正如他们所说天无绝人之路，我们已从所作的决定中汲取了教训。