Oblique cases of ko and šta

Since your first lessons you have asked Ko je to? (Who is that?) and Šta radiš? (What are you doing?). In both, ko and šta are the subject or a plain object. But English also asks whom did you see, who did you give it to, what are you afraid of, who are you going with — and in Serbian the question word itself changes in each of these, exactly like a noun changes its case.

The rule is simple to state: ask with the form the answer would have. If the answer is Čekam brata (accusative), the question is Koga čekaš? If the answer is Pišem mami (dative), the question is Kome pišeš? The verb or the preposition chooses the case, and ko or šta takes it.

ko — asking about people

koga is both the accusative and the genitive, just like an animate masculine noun (vidim brata, kod brata). So never say Ko vidiš? — the person you see is an object: Koga vidiš? The short forms kog and kom also exist in speech; this lesson uses the full forms.

šta — asking about things

The trap is the other way round from ko: šta does not change in the accusative. Šta vidiš? is right, because a thing in the accusative looks like its nominative (vidim sto). Only the genitive, dative, locative and instrumental use the č- forms.

The verb chooses the case

You already know verbs that want a case other than the accusative. The question word simply follows them:

• bojati se, sećati se, plašiti se take the genitive: Čega se plašiš? Koga se sećaš?
• pomoći, verovati, radovati se take the dative: Kome veruješ? Čemu se raduješ?
• baviti se, ponositi se, upravljati take the instrumental: Čime se bavi tvoj brat?

After a preposition

A preposition always comes first and always forces a case, so learn each pair as one chunk. The preposition never moves to the end the way it does in English (Who are you going with? = S kim ideš?).

With an accusative preposition, šta still stays šta: Na šta misliš? (What are you thinking of?), U šta gledaš? But a person is still koga: Na koga misliš? (Who are you thinking of?)

neko, niko, nešto, ništa decline the same way

Put ne- in front and you get someone / something; put ni- in front and you get nobody / nothing. The endings are exactly those of ko and šta, so the answer to a question usually mirrors it: Kome si rekao? — Nikome.

With niko and ništa a preposition splits the word into three: ni + preposition + koga/čemu... So it is ni s kim, ni o čemu, ni od koga — never s nikim. With neko and nešto nothing splits: s nekim, o nečemu. And remember the verb is still negated: Ni s kim ne razgovaram.