That sentence doesn't make sense to me, in English. "The sandwich is there, isn't it?" works (definite article, so a specific "it"). I don't think the sentence works with an indefinite article.
"The sandwich is there, isn't it?" would be Tá an ceapaire ansin/ann, nach bhfuil? in Irish.
Ann can be used where you might use ansin, but Ceapaire atá ansin doesn't work, so this isn't one of those cases.
Indefinite works fine in English. As in:
Person 1: Paul said there isn't any more food in the refrigerator. Person 2: A sandwich is there, isn't it?
That's still ungrammatical nonsense. The fact that it makes some sort of sense to you doesn't make it grammatical (just look at all the people who say and write "could of").
"There is a sandwich (there), isn't there?" "It is a sandwich, isn't it?"
The phrase "a sandwich is there" itself is actually about "there", not about "a sandwich" - you are describing the contents of "there", (the refrigerator in your own example), so "isn't it?" doesn't make any sense as a clarifying question.
Wow. I have no idea what your English credentials are, but as a native-English speaking PhD, I beg to differ with your "ungrammatical nonsense" comment. But I am also not surprised --- in the six months I have been using the Irish program here, you have managed to respond to virtually every question or comment of mine with an astounding level of snark or rudeness. I can't guess whether you have a limited level of tact or are simply inherently nasty, but I would greatly appreciate if you would refrain from responding to any questions I ask on Duolingo in the future. Thankfully, there are at least several other Irish-speakers here who are knowledgeable, helpful, and seem able and willing to respond to learners without making learning Irish an unpleasant experience. Thank you.
I am going to attempt to answer my own question. While the FGB is helpful, what a teacher said to me might close the loop. Irish generally doesn't like to end a sentence with a verb. So in that situation "ann" is often added to close the sentence and can be thought of in English as "in there," "there," or "exists" if needed. However, in these cases the "ann" is just a closer and is not supposed to detract from the subject. The Duolingo translation does all the above even though, to me, that translation does pull the word "it" out of thin air.
Thats very helpful indeed. 'Ann' does in many cases just seem to be a weak existential place holder. Otherwise, you might parse this as a form of the 'quality bearing 'i' , as in 'Ceapaire atá i mo dheartháir', my brother is a sandwich'
You weren't far off the first time.
If you want to say "she is a ..." you can say ... atá inti.
Déagóir atá inti - "she is a teenager"
Bean chliste atá inti - "she is a clever woman"
bean as mo thír féin atá inti - "she's a compatriot of mine"
inti is the feminine 3rd person singular prepositional pronoun for i, and the the masculine form is ann, so ceapaire atá ann could be "he's a sandwich" (if you were talking about your brother), but usually it means "it's a sandwich".
By looking at examples using inti it's easier to see which ann is in play here.
Tá ceapaire ann - "there's a sandwich there" (or the clunkier "a sandwich is there").
ceapaire atá ann - "it's a sandwich"
Compare it to Rúnaí atá ionat - "You are a secretary". ionat is the 2nd person singular prepositional pronoun for i, and ann is the masculine 3rd person singular.
"He is a sandwich, is he not?" I thought this was a funny sentence until I checked here.
Duolingo does accept the slightly different (and more natural, for me) construction "isn't it", rather than the more stilted/formal sounding "is it not".
Sorry, I didn't even see there was a link there. I will go look. Thanks.
Just to be clear, this can be translated as "He's a sandwich, isn't he?", can't it? I know it's completely silly, but then again, so is Paul, the President of Ireland, putting women in a refrigerator.