求翻译：打开喷枪，关闭水源开关，然后立即关闭汽油机。（先关水，后关汽油机，目的为了让泵内的余水尽可能的排除，可有效的防止单向阀阀片生锈和黏住）是什么意思？

Open gun, turn off the water switch, then immediately turn off the gasoline engine. (First off the water, then turn off the gasoline engine, the purpose of exclusion as much as possible in order to allow the remaining water pump, which can effectively prevent one-way valve film rust and stick)

Turn off water gun, switch, and then immediately turn off gas. First off, after water, gasoline, and in order to allow the pump in the water as much as possible about the exclusion, and can be effective in preventing check valve, rust and stuck)

Turns on the spray gun, the closure water source switch, then closes the gasoline engine immediately.(Closes water first, latter turns off gasoline engine, goal in order to let in pump excess water as far as possible elimination, but effective prevented cone-way valve valve piece rusts and mounts)

Open the gun, water switch is turned off, and then immediately turn off the gasoline engine. (Turn off the water, turn off the engine after in order to pump water to exclude as much as possible, which can effectively prevent rust and stuck check valve valve plate)

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