海绵已经吸水到饱和状态，再也吸不进去了。

The sponge reached ___saturation and couldn't absorb any more water.

市场上同类型的健身应用已经饱和，很难再吸引新用户了。

The fitness app market has reached ___saturation, making it hard to attract new users.

这张照片的颜色饱和度太高了，看起来不太自然。

The ___saturation in this photo is too high, making it look unnatural.