"Ei învață limba română la Duolingo."

Translation: They learn Romanian at Duolingo.

[Rina_Irina]

Duolingo is a tool so it makes more sense to learn Romanian "with" Duolingo. Learning romanian "at" Duolingo refers to a place.

[Mediterran18]

Ai dreptate, învățând aici română îți strici engleză

The fact that Duolingo is a tool should not be used as an excuse. The programming should be better maintained. This error is not so serious, but in other examples it is!

[-Sveznalica-]

Oh come on! "They learn Romanian language at Duolingo." is not accepted, with the correction: They learn Romanian at Duolingo... Seriously!