Whether the gas valve is closed after the vehicle is turned off. . Whether all 4-cylinder cars are closed. . thank you

Well, first of all, that thing on the air inlet is called "throttle". The opening is controlled by the driver's accelerator pedal. After the flameout, the driver does not step on the accelerator, of course, the accelerator is closed.

The valves you mentioned are installed on the cylinder head, and their opening is driven by the camshaft. Nowadays, cars are all four-stroke engines, and the working conditions of each cylinder are different, which means that no two cylinders of a four-cylinder engine have the same stroke. So the elastic opening and closing are also different. Therefore, the valve is opened and closed at any time. It is impossible to close all valves, and it is impossible to open all valves.