This is a very good question. Unfortunately, it can't be explained clearly in a few words. This is also a research topic in linguistics. I share my experience with you. When I was in China, my English was always the best. I took the TOEFL in my sophomore year and came to the United States to study undergraduate. I have been in the United States for nearly 20 years, majoring in language, and I am very interested in this issue. My personal feeling is that you still have to memorize the basics of grammar and vocabulary. If you come to America, your pronunciation will be standard and your vocabulary will be rich. If you don't understand your words, let alone your pronunciation and vocabulary are not so perfect. But the sense of language is cultivated in the English environment in the United States for so many years, but I still have to go back to what I just said. You need grammar knowledge to develop a sense of language. Let's just say that some people in China are around. My knowledge of grammar is average, my English is average, and my daily life is fluent, but writing articles (many classes at school, after work, reports, papers, and many things to write) or making many mistakes when explaining things, many of them are caused by lack of language sense. For a simple example, many people know that the verb of the third person plus' s' is singular. But many people are prone to make mistakes when using it. Because he doesn't think "where to go" sounds awkward, he must master this grammatical phenomenon first. After a long time, "where to go" sounds awkward, which is the sense of language, so +s becomes "second nature" and can't be wrong! In fact, we have studied this +s matter, and there are many research reports in linguistics, so I won't go into details here.

Language sense needs to be cultivated by "total immersion" under basic conditions, and so does thinking. There must be a foundation of grammar and vocabulary, that is, basic skills, plus "total immersion", both of which are indispensable.

I write too much, and everyone looks tired. Talk to me again if you are interested.