Distance from point P to surface M: crossing point P makes the vertical line of surface M intersect with surface M at point O, and the length of PO is the distance from point P to surface M; Line-plane distance: Only when the straight line L is parallel to the plane M can there be a line-plane distance. Passing through any point P in L makes the vertical line of plane M intersect with plane M at point O, and the length of PO is the distance from straight line L to plane M; Face-to-face distance: Only when the N plane is parallel to the M plane can there be a face-to-face distance. Any point P passing through N plane is perpendicular to M plane and intersects M plane at point O, and the length of PO is the distance from N plane to M plane;