"Čí je tamten starý dům?"

Translation: Whose old house is that?

[ion1122]

Or, more literally, "whose is that old house" (which is also accepted).

Note that in the Czech sentence, "Čí" is used as a demonstrative pronoun, not as a demonstrative adjective.

[SomeStrang1]

When I click "Ci" here, I hear a longer czech sentence instead of just the word. Is that some error?

[VladaFu]

A known error https://forum.duolingo.com/comment/28047586

[Yvonne398816]

Whose is that old car? Why is that not accepted?

[VladaFu]

Because dům is a house, not a car.