My first thought was "I put an apple with an arrow through it on this table. Now tell me where is this particular apple now??" Short: Where is this apple?
Or even: "You keep talking about a special apple. Where is this apple (you keep mentioning)?
In both cases I do not know where 'this apple' is and have to ask for it. It does not sound strange to me at all, but as I am not a native english speaker, I may be wrong ...
As a native English speaker I can say that while the sentence is not as common, it is something that I would say. I think your second example about the special apple is a perfect example of its usage. To me, "Where is that apple?" is just as weird. In most cases I would just say, "Where is the apple?"
I think it might depend on the context. I'm not a native English speaker, but I would say "where is that (fu**ing) apple (I've just put here)?" in a situation when I have placed a particular apple somewhere e.g. to eat it later or prepare it for a cake, someone took it away without telling me and I'm frustrated because I can't find it anywhere.
Why can I not say "Where is the apple?" I was to the impression that "this" (это) could be translated like "the" in situations like this? Also, why is it это at all, instead of этот? I thought that "это яблоко" was "this is an apple", and that "этот яблоко" was "this apple"? What's up here?
Well except for the case, as someone above mentioned, in the somewhat existential case of some mysterious apple that people talk about or imagine. Then you might say in English, "Where is this apple" as in "Where is this mysterious and magic apple that everyone talks about" Or if it is a criminal investigation where it is alleged that an apple was thrown at someone and they are looking for the evidence. Then you might say, in English, "Where is this apple" as in "Where is this apple that was alleged to have been thrown at that person" :):) lol BUT....in the drop down for the word "это" used in this exercise, they have "the" as one of the meanings. So one would think either one should be accepted as correct. BUT I believe in Russian they do not use prepositions the way we do in English....certainly not as much. Therefore for "the apple" or "where is the apple" they would probably just say the equivalent of just "apple" and "where is apple" >>> яблоко and где яблоко? Да? Нет?
"Where is the apple" not accepted 18 Apr 2018. Reported.
This exercise is confusing because the genitive determine for "this apple" is это, which is the same as the generic это used in sentences like "Мама - это женщина" = "Mom is a woman".
Here, Duo appears to be using это as a specific determiner attached to яблоко, not as some sort of generic, so it means "this apple", a very particular and specific apple.
In English, however, instead of "this apple", we'd say "the apple". There are only a limited number of odd instances where we would ask, "Where is this apple?" As in, "I have the apple that the witch used to try to kill Snow White!" Response:"Oh yeah? Well, where is this apple?"
Mostly, though, you'd be asking where "the apple" is.
I chose "это" both times in this round, and both were marked incorrect though it is listed as the correct answer. I reported it each time.
Edit - Well now I'm stuck on this. It won't accept any answer (I tried every option). I'll have to quit the session and lose everything. Very disappointing.