Moraš da Imaš

After imati the noun goes into the accusative. That sounds like more work than it is, because half of these nouns don't change at all.

That highlighted row is the one that catches people. Hrabrost and radoznalost are feminine, but they end in a consonant, so they belong to a different declension entirely — the one where the accusative is identical to the nominative. Almost every abstract noun in -ost works this way: mladost, ljubaznost, radost, mudrost.

The second half of the exercise is about where you are. Serbian splits this cleanly: a place takes u or na with the locative, but a person takes kod with the genitive. You go u prodavnicu but kod lekara — literally "at the doctor's".

Whether a place takes u or na is not something you can reason out; it's fixed by usage. U hotelu, u muzeju, u crkvi — but na carini, na aerodromu, na pijaci.