当你在街上行走踢到了路障 你情不自禁地说了 shit 而不是 草

或看到一个乞丐在靠近你 你想都没想要用什么助动词就说 what the heck ARE you doing?!

Flow?
It’s something you subconsciously picked up in a language and you utilize it in a way that’s inexplicable?
For example I’ve been learning mandarin and recently I’ve read a lot of material on the words “怎么会” (how would/could)
It took me just a few classes to understand that it’s not only a way of asking a rhetorical question but also expressing the tone and mood of a person being frustrated.
“我怎么会知道?” How tf would I know? It’s a rhetorical question where the asker is not just expressing doubts about his or her knowing something, but it also shows a level of mild frustration.
You get this kinda flow by reading and immersing yourself in the target language.
If someone who’s a beginner in Mandarin and they ask me about “怎么会”，I wouldn’t be able to explain that properly without showing a bunch of examples first.

用英文思考，需要大量的语言环境浸泡

三岁孩子骑平衡车，
无道理可传给他，但他学得很快，特溜

你听过那几个声音在一起，你看过那几个词在一起，你知道它们可以与其它的哪些在一起。

用我的话说就是做完形填空的时候连选项都不看，读完一句话就觉得这个空只能是这个词

就是句子的感觉。错误的句子/表达，你会感觉怪怪的

这样说吧！
中文的语感又是怎样的呢？

应试教育这么几年 我依然无感