Single refers to the water depth.
"The water in this line is deep" means that every industry has hidden rules. If the water is deep, it shows that the hidden rules of this industry have formed a certain pattern. Only by fully understanding can we survive in this industry.
"This person is deep in water" means: this person is shrewd, thoughtful, scheming, not simple, and wily, and is generally used to remind someone to be wary of XXX, or with jealousy.
The water is deep, pinyin: [Shuǐhūn shēn]
Explanation:
Refers to the depth of water
Metaphor is the measure of speech and behavior.
Thick or light [color]
Example:
It rained all night, and the water in the yard was deep.
I thought this industry was easy to do, but when I came in, I found the water was deep.
Xiaoming's water is deep, so everyone must be careful.