What's wrong with "Ви не маєте сестру"? Duolingo gives the correct solution as "Ви не маєте сестри." I thought "а" changed to "у" in the accusative case for feminine words.
Я маю сестру - you need to use the accusative case here.
Я не маю сестри - you need to use the genitive case in a negative statement with "to have"
Is it correct as far as the English provided version is concerned??
Why not у тобі немає сестри?