Definition: A hidden thing or place is not easy to find. Level: B1
我们在山里发现了一个隐藏的山谷。
We discovered a ___hidden valley in the mountains.
房间里有隐藏的麦克风。
There were ___hidden microphones in the room.
他们为电视节目使用了隐藏摄像机。
They used a ___hidden camera for the TV show.
