As others have already noted, vocabulary is the most important aspect with regards to learning a language to a good-enough extent; that is, with regards to making oneself capable of constructing sentences (as non-grammatical as they may be, or as unconventional as they may sound to a native or to a fluent individual, in spite of being deemed "technically correct") that can be understood by other people competent in a…
> vocabulary acquisition shouldn't be constrained to the typical or more salient nouns and adjectives My recent research finding (that needs to be confirmed with new data I collected) is that East-Asian L2 learners of English have a gap in knowledge of adjectives/adverbs in comparison of nouns. The nouns causing them problem are in the 3000 frequency vocabulary band while the adj/adv they don’t know are in the 2000 f…
Listening is also a skill that people overlook. You need to train the ear to pick up how people pronounce a specific language otherwise it will just sound like noise. Let me give you an example: I have a 4 years old son. He likes cartoon. English speaking cartoon sounds like garbled noise to him. I know because he try to recreate the conversation and it came out like garbled noise. I prompt him with some word with Chinese translation before he watch video then gradually he can recognize the word in the video and gave me correct translation after I asked him.