Questions & Answers about Moja sestra danas nosi haljinu, a ja nosim pantalone.
Because moj/moja/moje works like an adjective in Serbian, so it must agree with the noun it describes.
- sestra is feminine singular
- so my sister is moja sestra
Compare:
- moj brat = my brother
- moja sestra = my sister
- moje dete = my child
So moja is the feminine singular form needed for sestra.
Sestra is in the nominative singular, because it is the subject of the clause:
- Moja sestra danas nosi haljinu
- My sister is the person doing the action
So the basic dictionary form sestra is used here.
Because haljina is the direct object of the verb nosi.
The verb nositi often takes the accusative case for the thing being worn or carried. So:
- haljina = dress, nominative
- haljinu = dress, accusative singular