"Are you talking to me?"
Translation:너 나에게 말하고 있냐?
If one wanted to express the same thing in posh-sounding, standard Korean (표준말), one should use 있니 (It-Nee) for 있냐 (It-Nya). Any interrogative sentences that end with 냐 (Nya) can be replaced by 니 (Nee). It sounds much more polite and less confrontational.
If one wanted to express the same sentence in formal Korean (존댓말), there are three ways as the following:
저한테 말하고 있는 거에요? (low-level formal, one could use this when talking to strangers or acquaintances or coworkers or distant relatives, e.g. uncles or aunts or cousin-uncles or cousin-aunts who are younger than you)
저한테 말하고 있는 겁니까? (medium-level formal, one could use this when talking to strangers or elders)
저한테 말씀하시는 겁니까? (high-level formal, one could use this when talking to elders or superiors at work, e.g. your company's president/CEO)
Ummm... my answer without 너 because it sounded more natural and it marked it as incorrect. Fix this please :) 감사합니다
너 (You) and 나 (Me) are informal, so it's natural to use 있냐 in this sentence. Besides, this "only-use-when-you're-close-or-when-situations-allow" type of speaking should be learned as well, since most Koreans will construct sentences like this around you. It's important to know the sentence structure of both Formal and Informal speech in Duolingo, and I'm glad they've included sentences like this.
The point here might be that it hasn't been taught yet in the course.
I have seen a comment from the "admin" (couldn't think of a better word, sorry) saying they won't use one word or another because it was not on the lessons, but then there are some sentences which escape even the grammar. Confusing, I have to say...
In the other hand, I see this as teaching some sentences "here and there" or because they are very common, or because they want us to get used to it. Not sure...