*Please be advised that the following is from a practice book, with minimal altering. I sincerely hope this sort of question does not disagree with anyone here.
The question in the book:
Below is how I see the problem.
First of all, according to this question, I believe it is safe to replace it with も here, although it is evidently too weak a statement.
Secondly, let's take a look at でも:
a.) If で is a variant of だ,
食べる時間でもない can literally be translated to "is not (the) time to eat either." Thus, out of the question.
b.) What if でも functions as "even" as seen in this question, defined as "
で 'in (the case of)' + も 'even, too'" by cauliflower cloudさん? This is where things start to fall apart for me. Is this simply wrong, or just unfit due to context and/or naturalness?
c.) What about で (as seen in a. above) + でも (as seen in b. above)? Although I assume it is unnatural, would it be correct grammatically speaking?
What's worse, the book provides these sample sentences:
1. 俺は今日吸う *タバコさえ* ないんだ… ( = タバコも)
2. そんな簡単な問題、 *犬でさえ* わかるよ！ ( = 犬でも)
I do not understand at all how in sample sentence 2, でも becomes possible again. Does it have anything to do with what the subject in the sentence is?
Here's an incidental example from a Japanese-teaching website (Wasabi). Again, でも seems perfectly fine to me, but is deemed incorrect:
The author of the article where the above sentence is from explains as follows, which regrettably makes no sense to me:
It’s wrong because it doesn’t imply any reasonableness.
Are all these instances a matter of grammar, or do they have more to do with context and suitable usage?
I apologize if I seem to be spamming this forum with questions lately. It's just that I've been stuck on this particular grammar problem for far too long. I've no choice but to resort to posting a new question here. There are several articles on the Net which deal with さえ and でも, but I honestly have not found one which hits the spot for my dull brain. I'd really appreciate it if someone would have another go at it for me. Thank you.