The most problematic for me as a non-native has been "the" vs "nothing", i.e. when one can/should put the definite article.
Pre-LLM I was joking that real AI is whatever can make that decision correctly 100% of times.
How do you feel about adjective ordering rules? I always wondered what this was like from the outside.
As a patron of the 405, there is no consensus.
Try making it with "a" - if thing can be "a thing" then it could be "the thing" but if it can't be "a thing" it definitely can't be "the thing" either.