"What is your question?"
Translation:Cad é do cheist?
Please validate if my understanding is correct.
With the question word "cad" you use the relative clause "atá" or "a + verb" in the question form if the affirmative form of the same sentence requires "tá" or "verb", respectively. And you do not use the relative clause in the question form if the affirmative form of the same sentence requires the copula "is". Instead the copula is considered to be hidden within "cad" somehow and you just use "é/í" after "cad" depending on the gender. So,
Affirmative form is "Is mo cheist é" hence "Cad é do cheist?"
Affirmative form is "Tá ... aici" hence "Cad atá aici?"
Affirmative form is "Ólann sí ..." hence "Cad a ólann sí?"
A bit of annoying is that you have to deduce the grammar rules by yourself every time without having a possibility at least to check right away if you have inferred them right. Maybe it is a good learning strategy for simpler languages like Norwegian with a lot of examples, but the strategy certainly carries unnecessary difficulties along for the languages with a complex grammar structure. Duolingo should have written more within the Tips and Notes this time. Instead the course creators are forced to do it in the comments over and over regardless. The difference is that it becomes difficult to find those explanations when you need them among the tonnes of irrelevant comments