Learn Hardcore Croatian: Ponekad sam zaboravan i ostavim mobitel na klupi u parku. - Sometimes I am forgetful and leave my phone on a bench in the park.

Ja sam zaboravan. – neutral, a bit more explicit; ja (I) is emphasized or contrasted with someone else.
Sam zaboravan. – very common in speech and writing; subject pronoun ja is dropped because the verb ending -am already shows the person.
Zaboravan sam. – also correct; it puts a bit more emphasis on the adjective zaboravan (forgetful), like saying “Forgetful, that’s what I am.”

In everyday neutral speech, (Ja) sam zaboravan is probably most typical, with ja usually omitted unless you need contrast or emphasis.

What exactly is zaboravan? How is it different from the verbs zaboraviti / zaboravljati?

Zaboravan is an adjective meaning forgetful – it describes a person’s general tendency or character.

zaboravan – forgetful (adjective):
- Ponekad sam zaboravan. – Sometimes I’m forgetful.

The verbs:

zaboraviti (perfective) – to forget (a completed act):
- Zaboravio sam tvoj rođendan. – I forgot your birthday.
zaboravljati (imperfective) – to forget (be in the process of forgetting, or to forget repeatedly/often):
- Često zaboravljam ključeve. – I often forget my keys.

In the sentence Ponekad sam zaboravan i ostavim mobitel…, zaboravan describes a character trait (“I’m a forgetful person”), while ostavim describes one of the results of that trait (I leave my phone on the bench).

Why is ostavim used here and not ostavljam?

Both exist, but they have different aspect:

ostaviti (perfective) → ostavim – I (will) leave / I (sometimes) leave (seen as single complete events)
ostavljati (imperfective) → ostavljam – I am leaving / I (habitually) leave (viewed as an ongoing or repeated process)

With ponekad (sometimes), you can use ostavim or ostavljam:

Ponekad ostavim mobitel na klupi. – Sometimes I leave my phone (each individual act is seen as a complete, occasional event).
Ponekad ostavljam mobitel na klupi. – Also possible; sounds a bit more like a recurring bad habit, highlighting the repeated process.

Native speakers often choose ostavim with ponekad; it treats each “leaving” as a distinct, completed event that occasionally happens.

Could I say Ponekad zaboravim mobitel na klupi u parku instead? Is that the same meaning?

It’s close in meaning but not identical:

Ponekad sam zaboravan i ostavim mobitel na klupi u parku.
Literally: Sometimes I am forgetful and (as a result) I leave my phone on the bench in the park.
→ Focuses on your personality (forgetful) and one typical consequence.
Ponekad zaboravim mobitel na klupi u parku.
Literally: Sometimes I forget my phone on the bench in the park.
→ Focuses directly on the action of forgetting the phone, not on being a forgetful person in general.

Both are natural; you just shift the spotlight: character trait vs. specific action.

What case are klupi and parku, and why do they have those endings?

Both klupi and parku are in the locative case singular, used with certain prepositions (like na, u) to express location.

klupa (bench) → locative singular: (na) klupi – on the bench
park (park) → locative singular: (u) parku – in the park

The pattern:

Feminine noun klupa:
- nominative: klupa
- locative: klupi after na → na klupi
Masculine noun park:
- nominative: park
- locative: parku after u → u parku

So the prepositions na and u trigger the locative case here, which changes the endings.

How do I know when to use na and when to use u, like na klupi but u parku?

Na usually means on (a surface, an open area, an event), and u usually means in / inside (an enclosed space, a group).

In this sentence:

na klupi – on the bench (you put the phone on the surface of the bench)
u parku – in the park (the park is seen as an area you are inside)

Common patterns:

na stolu – on the table
na plaži – on the beach
u sobi – in the room
u kući – in the house

There are idiomatic exceptions, but as a rule of thumb: na = on/open place, u = in/inside.

Can ponekad go in other positions in the sentence?

Yes. Ponekad (sometimes) is quite flexible. All of these are possible:

Ponekad sam zaboravan i ostavim mobitel na klupi u parku.
Ja sam ponekad zaboravan i ostavim mobitel na klupi u parku.
Ja sam zaboravan i ponekad ostavim mobitel na klupi u parku.

Differences are subtle:

Ponekad sam zaboravan… – “Sometimes I’m forgetful…” (modifies being forgetful)
sam ponekad zaboravan… – similar, a bit more balanced inside the verb phrase
…i ponekad ostavim mobitel… – “and I sometimes leave my phone…” (emphasis shifts slightly to the action of leaving)

All are natural; word order in Croatian is flexible and often reflects what you want to emphasize.

What does i do here? Is it exactly like and in English?

Yes, i is the basic coordinating conjunction meaning and.

In the sentence:

…sam zaboravan i ostavim mobitel…
→ i links two predicates/actions of the same subject: “I am forgetful and (I) leave my phone…”

Other examples:

Marko i Ana. – Marko and Ana.
Čitam i pišem. – I read and write.

So here i works just like English and.

If the speaker is female, does anything in the sentence change?

Yes, the adjective zaboravan must agree in gender with the subject.

Male speaker: Ponekad sam zaboravan i ostavim mobitel na klupi u parku.
Female speaker: Ponekad sam zaboravna i ostavim mobitel na klupi u parku.

Only zaboravan → zaboravna changes.
The verb sam and ostavim stay the same; Croatian verbs in the present tense do not change for gender, only for person/number.

Could I leave out u parku or na klupi and still have a correct sentence?

Yes. Both are optional details of place:

Ponekad sam zaboravan i ostavim mobitel. – Sometimes I’m forgetful and (I) leave my phone.
Ponekad sam zaboravan i ostavim mobitel na klupi. – …and leave my phone on the bench.
Ponekad sam zaboravan i ostavim mobitel u parku. – …and leave my phone in the park.

All are grammatically correct. You just lose or change some information about where you leave the phone.

Why is there no word like a / the before mobitel, klupi, or parku?

Croatian does not use articles (no a / an / the). Nouns appear without them:

mobitel – (a / the) mobile phone
klupa / klupi – (a / the) bench
park / parku – (a / the) park

Context normally tells you whether English would use a or the. So:

ostavim mobitel na klupi u parku
could be translated as
“I leave my phone on the bench in the park”
or, in other contexts, perhaps “a phone on a bench in a park”.

The Croatian sentence itself doesn’t mark definiteness with an article.

The Croatian sentence is in the present tense. Does it talk about a habit, like in English I sometimes leave my phone?

Yes. Croatian uses the present tense to talk about:

Actions happening now, and
Habits and general truths, just like English.

Here:

Ponekad sam zaboravan i ostavim mobitel…
is about a repeated, habitual situation: “Sometimes I’m forgetful and (I) leave my phone…”

So the present tense with an adverb like ponekad (sometimes), često (often), uvijek (always) naturally expresses habitual actions in Croatian.