"Iu tago la radikoj de tiu arbo detruos la muron."
Why is this wrong? I feel it should be a valid answer, but I am not that sure to report it. Duolingo only accepts "Iutage" instead of "Iu tago".
I did the same thing. Maybe "Iu tago" is wrong because it's just a noun that's not doing anything. I'll bet that "Je iu tago" (on some day) might be legitimate. I don't know for sure, though.
I think you could be right with "Je iu tago". Any "spertulo" here?
Stultulo ĉi tie. Duo nun akceptas kaj 'je iu tago' kaj 'iun tagon'
La Vortaro at LernuNet says: "iutage (iu·tag·e ← tag·o) = one day, someday"
Either "iutage" or "iun tagon" would be correct.
The Esperanto here now is "Iam la radikoj de tiu arbo detruos la muron". I thought "iam" means sometime. Don't you need to say "iam tage" or something similar to mean some day?