Have you found the cause of the breakfast? 

你们找到了破损的原因吗?

 

It is obvious that it was due to careless packing. 

很明显包装太马虎了。 

 

We'll let you know when we find out the reason. 

我们查明原因后会通知贵方。 

 

 

find out(找出，查明，发现) 

 

Tip: find out表示查明(真相等);查出……的罪行;揭发出;使受惩罚(或报应)，如:查明(真相等): I'll find out her secret. (我要弄清她的秘密。), All you have to do is to find out the KEY to escape. (你所要做的就是找到藏在某个馒头里的钥匙然后逃跑。)另外还有"对(某弱处)起作用"的意思，如: This cold weather finds out my old wound.这个寒冷的天气使我的老伤发作了。