Breakdown of Ne znam koga su pozvali.
biti
to be (sam, si, je)
ne
no, not
znati
to know
pozvati
to invite (perfective)
Questions & Answers about Ne znam koga su pozvali.
Why do we use koga here instead of tko?
Koga is the accusative form of the pronoun tko (who). Because the people being invited are the direct object of the verb pozvali (invited), we must use the accusative case. It works just like the English distinction between "who" and "whom".
Wait, isn't koga also the genitive form of tko?
Yes, it is! Just like masculine nouns that represent living beings (animate nouns), the interrogative pronoun tko has the exact same form for both the genitive and accusative cases: koga. In this specific sentence, its role as a direct object makes it accusative.
Why is the auxiliary verb su placed right after koga?
The phrase koga su pozvali is a dependent clause. In Croatian, dependent clauses act like their own mini-sentences for word order. The question word koga takes the first spot in this new clause, so the strict "second position" rule forces the clitic su to immediately follow it.
Could pozvali also mean "called" in this sentence?
It could, as pozvati means both "to invite" and "to call" (such as calling someone over). However, if you specifically mean calling someone on the telephone, Croatians typically use the verbs zvati or nazvati instead.