概率问题公式简介：It was just a huge forest with twists and turns and criss-crossing paths. It was really not easy to find a place. The two of them walked for an hour and still couldn't find the hill marked on the map.
It was just a huge forest with twists and turns and criss-crossing paths. It was really not easy to find a place. The two of them walked for an hour and still couldn't find the hill marked on the map.
