The arch may be planar or three-dimensional, and the arch may be a part of a circle or a cylinder, and sometimes a part of the sphere may be a parabola or a part of an ellipse. When the arch is pressed, this force is transmitted to the adjacent part to withstand the force radiated by the arch foot to withstand greater pressure. Therefore, the arch can withstand more weight. The two hemispheres can be combined into one sphere, and the sphere can also be seen as a combination of several arches, the spheres being arched in all directions. Any part of the sphere is stressed, and the force can be evenly spread around, which is the same as the arch, so the sphere is stronger than any shape. This is the reason why a huge oil storage tank is made into a spherical shape. In order to make the light bulb more transparent, the glass shell is very thin, but it is made of a spherical shape, and it is relatively strong. Such as egg arch bridge shells, arched doors and windows, tunnels, are arched, but the lid and umbrella are dome-shaped, it has the characteristics of arched large pressure and no external thrust.