>>13552520well i think the bigger difficulty she has is understanding such questions which isn't helped by the fact that these people can't clearly communicate their confusion
really the person wasn't sure how to know when they should include な or not so the answer would simply be that from what we've covered so far な is only used when the adj is directly before a noun that it's modifying much like the nounのnoun pattern.
what the person instead asked was for what purpose な gets "dropped" in almost every pattern we've learned so far, in which case the answer involves explaining that all な adj are actually also nouns which then leads to many more questions since we've learned incomplete information up to this point.
for example you then need to explain that some nouns actually can take either な or の when being used as an adj while others can't be used as adj at all but generally only one or the other can be used.
in the same vein we were taught that you could say 面白くて易しい人 to describe someone who is both funny and kind, but for whatever reason they didn't explain that 面白くて is just the て form of 面白い, so then you need to explain that で in 元気で静かな人 is actually the て form of です so 元気 is still a noun in this case as well. then naturally based on that someone might ask if changing the structure to be 人は元気で静かです is also fine.
so you see the question the person actually asked requires quite a bit of explanation in order to avoid conflicting with stuff we've learned so far and it gets quite complex even though the question they meant to ask is very simple
>>13552538lol