如何用vrml表达月球自转,又绕地球公转,又和地球一起绕太阳转,

#VRML V2.0 utf8Background {skyColor 0 0 0 }DEF\x05sun Transform {\x05children [Shape {appearance Appearance {\x05texture ImageTexture {url "sun.jpg"}\x05\x05material Material\x05{}}geometry Sphere {ra...