Nilecat wrote:
In the following usage, you can assume the で as “te-form of です” (助動詞)
その食事のときに使ったのはおはしでご飯を食べました。
But in the following usage, it is a particle. (助詞)
私はいつもおはしでご飯を食べます。
Nilecat-san, you're not adding oil, thank you very much for providing us these two sentences, the comparison is helpful for clarification.
This 「おはしでご飯を食べます。」 was actually quoted from
this thread. I don't know OP, but from the posts, one can tell s/he is really confused with even the basic usages. I can't think of any good pointers to help her/him, except that I wish to focus on the PARTICLE DE, so as not to confuse him/her further.
I think every teacher teaches different things, but for me, I have never come across particle de as "te form of desu" until I get to the intermediate stage. My understanding of "te form of desu" as such: 名詞 + で(だ・です)+ある, in this sentence, it functions as 助動詞。
テキストブックには「鯨は哺乳類である」と書いてある。
In the book, it says that "whales are mammals".
From what I learn I've always thought that the basic 助詞 で is different from 助動詞で, my only curiosity is how does a teacher explain to learners when s/he presented this sentence 「みんなで行った遠足は楽しかったです。」(The excursion we went with everyone was an enjoyable one.)