C483 Mountain stronghold

Fu Shengbing frowned slightly, and said: "Oh right, Lao Zhao, there's something I don't understand. When I was buying the car, the Salesman did hit the sandbag until it flew around randomly. The range of the sandbag was very wide, but when you shot it up, why did the sandbag not even move at all? "

I thought that Fu Shengbing was really observant, but she had some knowledge about mechanics