Questions & Answers about Moju sestru boli stomak danas.
Because moju sestru is in the accusative case.
With the verb boleti (to hurt / ache), Serbian usually treats:
- the person who feels the pain as the object
- the thing that hurts as the subject
So in Moju sestru boli stomak, my sister is the one affected, so she appears in the accusative:
- moja sestra = nominative, my sister
- moju sestru = accusative, my sister as the object
Both words change because moju has to agree with sestru in gender, number, and case.
Here stomak is actually the subject of the sentence, so it is in the nominative.
That may feel backward to an English speaker, because English usually says something like My sister’s stomach hurts or My sister has a stomachache. But Serbian uses the pattern:
X boli Y = X hurts Y
So here:
- stomak = the thing that hurts
- moju sestru = the person who is hurt
One small complication: for many masculine inanimate nouns, the nominative and accusative forms look the same. So stomak could look unchanged either way, but in this sentence its function is nominative.