How plane stay in sky?

Someone ask: How plane stay in sky?

Plane stay in sky because wings push air down and air push plane up. Fast-moving air flow over wing make lower pressure above and higher pressure below, like river rushing over rock and piling water under it. Engine give plane speed, so wing can keep making enough lift. Plane also point nose a little up and keep moving forward; lift balances weight when flight work right. If plane go too slow, wing cannot push enough air, like spear thrown weakly into wind. Cave wisdom: sky does not hold plane up; plane shove air, and air shove back.