Learn Hardcore Croatian: Ponekad raspravljaju o prošlosti, sadašnjosti i budućnosti kao da su tri različita grada. - Sometimes they discuss the past, the present and the future as if they were three different cities.

Katkad – practically the same as ponekad, often a bit more formal or literary.
Povremeno – occasionally, now and then, often sounds a bit more formal.

In everyday speech ponekad is probably the most neutral and common choice for sometimes.

What is raspravljaju? Which verb does it come from, and what does it literally mean?

Raspravljaju is the 3rd person plural present tense of the verb raspravljati (to discuss, to debate).

Infinitive: raspravljati
Person/number: oni/one/ona raspravljaju – they discuss
Aspect: imperfective (it describes an ongoing or repeated action).

So Ponekad raspravljaju = Sometimes they discuss / have discussions.

Why is there no oni (they) in the sentence? Can I add it?

Croatian usually drops subject pronouns because the verb ending already shows who the subject is.

Raspravljaju alone clearly means they discuss.

You can say Oni ponekad raspravljaju o… if you want to emphasize they (for example, in contrast to someone else), but in a neutral sentence it is more natural to leave oni out.

Why is the preposition o used with raspravljaju? Is it like “about” in English?

Yes, o here corresponds to English about. With the verb raspravljati, you almost always use o for the topic:

raspravljati o nečemu – to discuss something / to discuss about something

Grammatically, o always takes the locative case, which is why you see o prošlosti, sadašnjosti i budućnosti (not the simple base forms).

What case are prošlosti, sadašnjosti, budućnosti in, and what are their dictionary forms?

All three are in the locative singular, because the preposition o requires the locative.

Their dictionary (nominative singular) forms are:

prošlost – the past
sadašnjost – the present
budućnost – the future

The locative singular of these feminine nouns ends in -i: prošlosti, sadašnjosti, budućnosti.

In English we say “the past, the present, the future”. Why is there no word for “the” in Croatian here?

Croatian has no articles (no a/an/the).

Definiteness is usually understood from context, word order, or additional words, not from a separate article.
So prošlost, sadašnjost i budućnost can mean the past, the present and the future when the context makes them specific, as it does here.

What does kao da mean, and how is it used?

Kao da means as if / as though. It introduces a subordinate clause describing an unreal or imaginary comparison:

…kao da su tri različita grada. – …as if they were three different cities.

You can use kao da with:

the present tense (as here) – often for vivid or figurative comparisons
the conditional – to stress unreality even more, e.g. kao da bi bila…

Why is the verb su placed right after da? Could it go somewhere else?

Su is the short (clitic) form of jesu, from the verb biti (to be). Croatian clitic verbs (like sam, si, je, smo, ste, su) must appear in the second position in their clause.

In …kao da su tri različita grada, the clause after da starts with su in that “second position” spot, so its place is fixed by this rule.
You cannot move su to the end (kao da tri različita grada su) – that sounds wrong in standard Croatian.

Who or what is the subject of su in kao da su tri različita grada?

The logical subject is prošlost, sadašnjost i budućnost (from the previous part of the sentence). Croatian does not repeat them; they are understood.

So you can think of it as:

(Prošlost, sadašnjost i budućnost) su tri različita grada.
The phrase tri različita grada is the predicative complement (three different cities), describing what the subject is “like” in this comparison.

Why is it tri različita grada and not tri različiti gradovi?

With the numbers 2, 3, 4 in Croatian there is a special pattern:

The noun is usually in genitive singular:
- jedan grad – one city
- tri grada – three cities (g.sg grada)
The adjective typically has the ending -a here:
- tri velika grada – three big cities
- tri različita grada – three different cities

So tri različita grada is the normal, grammatical way to say three different cities.
Tri različiti gradovi sounds unnatural and ungrammatical in standard Croatian.

What case is tri različita grada in here?

Syntactically, the whole phrase tri različita grada is in the nominative, because it is the complement of su (are).

Inside that phrase:

tri is nominative,
grada has the genitive singular ending (the normal pattern after 2–4),
različita is in the special “counting” form that appears with 2–4.

You don’t usually need to label this in detail; just learn that after tri you say tri + (adjective in -a) + (noun with its “2–4” form): tri različita grada.

Why does the adjective end in -a (različita) when grad is masculine?

After the numbers 2, 3, 4, adjectives normally take this -a ending, regardless of the noun’s gender:

dva nova stola – two new tables (masc.)
tri različita grada – three different cities (masc.)
četiri lijepa sela – four beautiful villages (neuter)

So you don’t use različiti here. The pattern “number 2–4 + adjective in -a + special noun form” is something you mostly learn by example and practice.

Could the word order be changed, for example Raspravljaju ponekad… or Ponekad oni raspravljaju…?

Yes, Croatian word order is relatively flexible, but it affects emphasis:

Ponekad raspravljaju o… – neutral, default: Sometimes they discuss…
Raspravljaju ponekad o… – still possible, but ponekad is less prominent.
Oni ponekad raspravljaju o… – emphasizes they (those people, not others).

The original order is the most neutral and natural in standard usage.