2. Considering the situation in real life, if a single door opens outwards, it may be easy for the door panel to accidentally hit people waiting to open the door outside, causing fright or even injury. If someone accidentally bumps into it, the light person will pay for the medical expenses, and the heavy person may accidentally affect the psychological state of the visitor and even have a knot. In the unconscious uncomfortable state, it may adversely affect the reputation of households and families, thus causing various tangible and intangible property or reputation losses. If the door opens inward, the person who opens the door will pay attention to avoid the door and not let it pinch him. It not only protects itself, but also protects the safety of people waiting to open the door outside. And if the door is open outside, if the outdoor wind is too strong, the open door will turn back in the case of strong wind. Light ones may touch or pinch people, while heavy ones may cause the gate to fall off.