In the figure, the symbol on the fuel tank switch that looks like a full glass of water is the positive fuel tank, that is, the symbol on the lower half of the glass of water is the auxiliary fuel tank, which is hidden from view by the handle of the fuel tank switch in the figure, and the symbol in the middle is closed. The arrow on the handle of the fuel tank switch. Pull the handle of the fuel tank switch to make the arrow point to which symbol and which function to use. As shown in the figure, pull the handle to the bottom, so that the arrow on the handle is up, indicating that the positive fuel tank is used, and vice versa.