"Acestea sunt inelele mamelor."

Translation: These are the rings of the mothers.

[alur_blaze]

Do the rings have to be articulated? Or, more broadly, when a noun has a genitive/dative noun responding to it, does it have to be articulated?

[efalc]

I learned that with the (possessive) genitive, yes, the noun must have the "definite" article. Think of it as a reinforcement that they are not just any rings, or rings in general, but specifically those that belong to the mothers.

[lulubeck]

These are the mothers' rings.

[Glenn_ski]

Yet another sentence you would never have a chance to say outside of Duo's sandbox.

[Dan878472]

Perhaps you are looking for a phrasebook of useful sentences. Duo is not a phrase book..there are dozens of those out there. The point is to help you understand the relationship of words in the sentence, and then you can eventually build your own sentences which is difficult to do with a Phrasebook which does not teach grammar.

[GrantHanha]

Duolingo is making me start to doubt my command of my mother tongue of English.