Distance between two points on a plane to the sum of the point value of the set (the value is greater than the distance between two points, usually called 2a), which is also known as the two fixed focus of the ellipse, the distance between the focal point is called the focal length; put the ball on one of the ellipse focus, regardless of combat in any direction, as long as through the wall opposite the oval rebound, the ball will fall in another focal point of the cave. Booth: flame retardant resin fiberglass gel coat; a main frame: built steel frame, surface spray anti-rust paint; colored: green paint quality after the first colored baked plastic; corners: before forming a professional polish, rounded edges and corners countertops button: no power. . Exhibits main timber: artificial stone, LED and so on. Wuhan Star Popular Science Technology Co., Ltd. Main products include: science exhibits, teaching equipment, laboratory boxes, Science and Technology Museum building, children's play equipment, laboratory construction, primary and secondary school general education equipment, science and technology museum exhibits, multimedia teaching equipment, such as vocational education, Warmly welcome all dealers or professional bodies to cooperate with us to jointly develop the market and contribute to the science and education.