For example, camera traps are a common tool used by biologists to take pictures of shy animals hiding in the forests, but these are motion-activated cameras, so they snap a picture every time an animal crosses their path.
例如，相机陷阱 是生物学家们通用的给那些藏在树林里 的害羞的动物拍照的方法， 但是这些是触发式的相机， 当一个动物穿过它们的路径时 才会拍照。