Learn Hardcore Croatian: On je napredan učenik hrvatskog i brzo razumije složene rečenice. - He is an advanced student of Croatian and quickly understands complex sentences.

učenik hrvatskog (jezika) = a student of Croatian (language)
- učenik – student (nominative singular)
- hrvatskog – genitive singular of the adjective hrvatski (Croatian), agreeing with the understood noun jezika (language).

You can think of it as literally: "student of Croatian (language)", and of → genitive in Croatian.

So:

učenik matematike – student of mathematics
učenik hrvatskog (jezika) – student of Croatian (language)

Why napredan učenik and not something like učenik napredan?

In Croatian, adjectives normally come before the noun they modify.

napredan učenik = an advanced student
- napredan – adjective, masculine singular, nominative
- učenik – noun, masculine singular, nominative

You can put the adjective after the noun in special stylistic or poetic contexts, but in normal speech and writing adjective + noun is the rule:

dobar čovjek – a good man
mlada žena – a young woman
napredan učenik – an advanced student

What’s the difference between napredan and napredni? Could I say On je napredni učenik hrvatskog?

In this sentence, napredan is the most natural choice.

napredan učenik – sounds neutral and everyday, meaning an advanced student.
napredni učenik – grammatically possible, but can sound more technical or marked, often used with things like technology or advanced groups:
- napredna tehnologija – advanced technology
- napredni razred – advanced class/group

With učenik, napredan učenik is what Croatians would usually say in a simple, natural sentence like this.

Why is it On je napredan učenik, with je in the second position?

The verb je (3rd person singular of to be) is a clitic in Croatian, and clitics generally want to stand in the second position in the sentence, after the first stressed word or phrase.

So:

On je napredan učenik... – On is the first stressed word, je comes right after it.

You could also say:

Napredan je učenik hrvatskog. – Here Napredan is first, and je still comes second.

But Je on napredan učenik... is wrong in standard Croatian. The clitic je cannot start the sentence.

Could I just omit On and say Je napredan učenik hrvatskog i brzo razumije složene rečenice?

You can omit On, but you cannot start the sentence with je.

Correct options:

On je napredan učenik hrvatskog... – with the pronoun.
Napredan je učenik hrvatskog... – no pronoun, adjective first.
Napredan učenik hrvatskog je i brzo razumije složene rečenice. – also possible, with a different emphasis.

Incorrect:

Je napredan učenik... – clitic je cannot be first.

Why is it razumije and not something like razumi or razumje?

Razumije is the correct 3rd person singular present tense of the verb razumjeti (to understand).

Conjugation (present tense):

ja razumijem – I understand
ti razumiješ – you understand
on/ona/ono razumije – he/she/it understands
mi razumijemo – we understand
vi razumijete – you (pl/formal) understand
oni/one/ona razumiju – they understand

Spelling points:

It’s razumije, not razumi (that would look like an imperative of a different verb)
It’s razumije, not razumje – the correct combination is ije.

What tense and aspect is razumije?

Razumije is:

Present tense
From the imperfective verb razumjeti

Imperfective aspect describes ongoing, repeated, or general actions:

On brzo razumije složene rečenice. – He (generally) quickly understands complex sentences.

A perfective partner verb would be razumjeti used in a perfective sense in certain contexts (e.g. razumjeti / shvatiti to come to understand something at a point in time), but in everyday speech you very often see just razumjeti for the general idea of “understand”.

Why is the adverb brzo placed before the verb? Can I say On razumije brzo složene rečenice?

Both positions are possible, but they differ in naturalness and emphasis.

On je napredan učenik hrvatskog i brzo razumije složene rečenice.
– Very natural. Focus is on the speed of understanding; brzo modifies razumije.
On je napredan učenik hrvatskog i razumije brzo složene rečenice.
– Grammatically okay, but sounds less natural and can be interpreted as if brzo is more tied to složene rečenice (as if quickly-complex sentences), or just slightly odd rhythm.

Default position in Croatian is usually:

Adverb + verb: brzo razumije, dobro govori, često čita.

Why is it složene rečenice and not složena rečenica?

Because the sentence talks about plural “complex sentences”, and složene rečenice is the correct accusative plural form.

Base forms:

složena rečenica – a complex sentence (feminine singular, nominative)
složene rečenice – complex sentences (feminine plural, nominative and accusative)

In this sentence:

razumije što? – understands what? → složene rečenice
→ direct object → accusative case
→ feminine plural accusative = složene rečenice.

So:

sg: On razumije složenu rečenicu. – He understands a complex sentence.
pl: On razumije složene rečenice. – He understands complex sentences.

Why does složene change its ending? What is it agreeing with?

Složene is an adjective meaning complex and it must agree with rečenice in:

gender: feminine
number: plural
case: accusative

rečenice (here) = feminine plural accusative
So složene must also be feminine plural accusative:

složena rečenica – singular, nominative
složenu rečenicu – singular, accusative
složene rečenice – plural, nominative/accusative

This is standard adjective–noun agreement:

dobre knjige – good books
teške vježbe – difficult exercises
složene rečenice – complex sentences

How would the sentence change if we talk about a female student instead of a male one?

You need to change the forms to feminine:

Ona je napredna učenica hrvatskog i brzo razumije složene rečenice.

Changes:

On → Ona (she)
napredan → napredna (feminine singular adjective)
učenik → učenica (female student)

The rest (hrvatskog, brzo razumije složene rečenice) stays the same.

Why is hrvatskog not capitalized? In English “Croatian” is capitalized.

In Croatian, adjectives of nationality and language are written with a lowercase letter.

So:

hrvatski jezik – Croatian language
hrvatskog – of Croatian (language)
engleski jezik – English language
talijanski jezik – Italian language

You only capitalize proper nouns:

Hrvatska – Croatia (country)
Hrvat, Hrvatica – a Croat (man, woman)

But:

hrvatski (adjective) – Croatian → lowercase.

Can I say učenik hrvatskog jezika instead of učenik hrvatskog?

Yes, absolutely. Both are correct:

učenik hrvatskog – short, very common in speech.
učenik hrvatskog jezika – more explicit (student of the Croatian language), common in more formal or precise contexts.

In everyday use, učenik hrvatskog is enough and sounds natural.

I’ve seen both hrvatskog and hrvatskoga. What’s the difference?

Both are genitive singular masculine/neuter of hrvatski:

hrvatskog – short form
hrvatskoga – long form

In this sentence, both are grammatically correct:

učenik hrvatskog jezika
učenik hrvatskoga jezika

Difference:

hrvatskog – more common in everyday modern speech.
hrvatskoga – can sound a bit more formal, poetic, or old-fashioned in some contexts.

How would I negate the sentence?

You need to negate both je and razumije:

On nije napredan učenik hrvatskog i ne razumije složene rečenice.
– He is not an advanced student of Croatian and does not understand complex sentences.

Key points:

je → nije in negation of to be:
- On je → On nije
razumije → ne razumije:
- negation by adding ne in front of the verb (except for to be in the present, which fuses: je → nije).

Is there a comma before i in Croatian here, like in English “..., and quickly understands ...”?

In this sentence, no comma is used before i in standard Croatian:

On je napredan učenik hrvatskog i brzo razumije složene rečenice.

Croatian usually does not use a comma before i when it connects two predicates with the same subject in a simple sentence.

A comma can appear before i in different structures (e.g. joining whole clauses with different subjects, or for emphasis), but not in this particular kind of sentence.