原来他们之前已经见过面了。

It ___turned ___out that they had already met before.

结果发现，是她解开了这个谜团。

It ___turned ___out she was the one who solved the mystery.

那声响动原来只是巷子里的一只猫。

The noise ___turned ___out to be just a cat in the alley.