Learn Hardcore Croatian: Ne mogu naći ključ u sobi. - I can’t find the key in the room.

In Croatian, the clitic ne negates the finite (conjugated) verb. Here, mogu is the only conjugated verb, and naći is an infinitive. So the natural form is Ne mogu naći…. Placing ne on the infinitive (e.g., “mogu ne naći”) is unidiomatic in Croatian.

What form is naći, and why is it used after mogu?

Naći is the infinitive, and it’s perfective aspect (“to find” as a completed action). Croatian modals like moći (can), morati (must), htjeti (want) typically take an infinitive: mogu naći, moram ići, želim učiti.

Could I use pronaći or nalaziti instead of naći? What’s the difference?

Naći and pronaći are both perfective (“to find” as a single, completed event). In this sentence, Ne mogu naći/pronaći ključ… are both natural.
Nalaziti is the imperfective (“to be finding / to find repeatedly”). Ne mogu nalaziti ključ would suggest you can’t habitually/regularly find the key—odd in this context. For a single search, stick with the perfective.

What case is ključ, and why doesn’t it change form?

Ključ is a masculine inanimate noun in the accusative singular, functioning as the direct object of naći. For masculine inanimate nouns, the accusative singular equals the nominative singular, so it stays ključ (not “ključa,” which would be genitive).

Why is it u sobi and not u sobu?

The preposition u takes:

Locative for location (Where?): u sobi = “in the room.”
Accusative for motion into (Where to?): u sobu = “into the room.” Since the sentence is about a static location (where the searching happens), you use locative: u sobi.

What case is sobi, and what’s the base form?

Sobi is locative singular of soba (feminine noun “room”). With u indicating location, the noun goes to locative: u sobi.

Can I use na instead of u here?

Not in this context. U means “in(side).” Na means “on/at.” You’d say:

u sobi = in the room
na stolu = on the table
na poslu = at work For a room as an enclosed space, use u.

How would I insert “it” (the key) as a pronoun?

Use the clitic ga (masculine singular). The typical placement is second position in the clause:

Ne mogu ga naći u sobi. You can also front the place phrase for emphasis, but keep the clitic in second position:
U sobi ga ne mogu naći.

How flexible is the word order, and what changes with different orders?

Croatian word order is flexible for emphasis:

Neutral: Ne mogu naći ključ u sobi.
Emphasize the place: U sobi ne mogu naći ključ.
Emphasize the object (less common, marked): Ključ ne mogu naći u sobi. Meaning stays the same; the fronted element is highlighted.

How do I say this in the past?

Use the past of moći + infinitive:

If you’re male: Nisam mogao naći ključ u sobi.
If you’re female: Nisam mogla naći ključ u sobi. You can replace naći with pronaći without changing the meaning.

How do I turn it into a yes/no question?

Invert with li on the conjugated verb, or use a question intonation:

First person (self): Mogu li naći ključ u sobi?
Asking someone (informal): Možeš li naći ključ u sobi?
Polite/plural: Možete li naći ključ u sobi?

Does Croatian use double negation if I add words like “nowhere” or “never”?

Yes, negative words co-occur with ne:

Nigdje ga ne mogu naći. = “I can’t find it anywhere.”
Nikako ga ne mogu naći. = “I can’t find it at all.”

How do I pronounce the special letters in ključ and naći?

č = like “ch” in “chur ch.”
ć = a softer “ch,” somewhat between “t” and “ch” (lighter than č).
lj = a palatal “l,” similar to the “lli” in Italian “famiglia,” or “ly” in “million” said quickly. So: ključ ≈ “klyooch,” naći ≈ “nah-ch(y)ee” with a softer final consonant.

Why is there no “a/the” before “key” or “room”?

Croatian has no articles. Ključ can mean “a key” or “the key,” and soba/sobi can be “a room” or “the room.” Context provides definiteness.

Is there anything tricky about spelling or spacing here?

Always write ne separately from most verbs: ne mogu (but note fused forms with some verbs like nemam, neću, and with “to be”: nisam, nije, etc.).
Keep diacritics: naći (not “naci”), ključ (not “kljuc”). Without them, words can become ambiguous or look incorrect.