fade down的用法和樣例：
例句
- The density goes down exponentially with height.
分子密度隨著高度的上升而指數衰減。 - A view popular in physics is to start with uncharged electrons and cores, which are therefore both free and plane waves and can have any energy, and then fade in the charge.
物理學中流行的方法是從不帶電的電子和原子核出發，因為它們是自由的平面波，可以具有任意能量，並在帶電后衰減。
