I'm studying grammar from their book この一冊で合書きできる N3 but it doesn't provide much information about each point, just the general meaning, how it's formed and 3 example sentences, therefore I'm looking for extra information and sentences online while also asking chat GPT for further explanations.
Thing is, in less than 30 grammar points, I've already encountered a couple of grammar points that differ between the book and what I can find elsewhere, the most recent is this one:
~反面
意味: ~なところがあるが、反対に。。。
接続: 普通形（なA だ(X) -> な・である / Nだ(X) -> の・である）+ 反面
You can also find the same explanation from their YouTube channel (10:25, should open the video exactly at that point though)
【JLPT直前対策】1時間で🌟この動画1本で N3文法が終わる！ N3 grammar in 1 hour
I couldn't find any reference to that "の" anywhere, their example sentences also don't include it and also asked a Japanese friend who said that の doesn't sound natural.
I kind of refuse to accept that grammar is wrong since this book actually focuses towards the JLPT and it rather is really specific JLPT case, but as I said before this is not the first time that I encounter this scenario, so at this point I prefer to ask here since a high percentage of learners are using grammar books.
Thanks in advance.
by Neith720