In the real world, rats don't spend their lives in cages waiting for lights to turn on; these experiments don't capture the complex role that fear plays in a wild rat's life.
Kepler will watch them all for three-and-a-half years and wait for the light from any of them to dim ever so slightly. That could be the sign of a planet passing in front of its sun.
3
等待着光线,等待着人群,等待着鸟儿落上树枝。
Wait for the light, wait for the crowd, wait for a bird to land on the tree branch.