Ako ne završiš danas, možeš da pokušaš ponovo sutra.

This is very normal in Serbian.

After ako (if), Serbian often uses the present tense to talk about a future possibility:

• Ako ne završiš danas... = If you don't finish today...

So even though završiš is formally present tense, the whole clause refers to a possible future situation.

Also, završiš is a perfective present form, and perfective present often points to a completed future action in clauses like this.

The difference is aspect.

• završiti = to finish, to complete (perfective)
• završavati = to be finishing / to finish repeatedly (imperfective)

In this sentence, the idea is completing something by the end of today, so Serbian uses the perfective verb:

• Ako ne završiš danas... = If you don't finish today...

If you said Ako ne završavaš danas, it would sound unnatural here, because it would focus more on the process or habit, not on the completed result.

In Serbian, the negative particle ne normally goes directly before the finite verb:

• ne završiš = you do not finish
• ne možeš = you cannot
• ne znam = I do not know

So Ako ne završiš danas follows the standard Serbian pattern.

Because Serbian often omits subject pronouns when they are already clear from the verb ending.

• završiš already means you finish
• možeš already means you can
• pokušaš already means you try

So the sentence does not need ti.

You could add ti for emphasis:

• Ako ti ne završiš danas...

But that would sound marked, as if contrasting you with someone else.

In modern Serbian, it is very common to use:

• modal verb + da + present tense

So:

• možeš da pokušaš = you can try

This is one of the most common ways to express this idea.

You may also see an infinitive after some verbs in more formal or regional usage:

• možeš pokušati

That is also understandable and correct, but možeš da pokušaš is extremely natural in everyday Serbian.

Yes. After da, Serbian normally uses a present-tense verb form.

So:

• da pokušaš literally uses the present form
• but in meaning, it often corresponds to English to try or that you try

In this sentence:

• možeš da pokušaš ponovo sutra = you can try again tomorrow

So even though the form is present, the meaning depends on the whole construction.

Here, da introduces the second verb phrase after možeš.

The pattern is:

• moći + da + present

Examples:

• Mogu da dođem. = I can come.
• Možeš da sačekaš. = You can wait.
• Možeš da pokušaš. = You can try.

So in this sentence, da is functioning a bit like the English to in to try, although the Serbian structure is not identical.

Yes. Ponovo means again, and in this sentence it means try again.

• ponovo = again, anew
• opet = again

So these are both possible:

• možeš da pokušaš ponovo sutra
• možeš da pokušaš opet sutra

In many everyday situations, opet is very common in speech.
Ponovo can sound a little more neutral or slightly more formal, depending on context.

Because the sentence begins with a subordinate if-clause:

• Ako ne završiš danas, ...

When that clause comes first, Serbian normally separates it with a comma from the main clause:

• Ako ne završiš danas, možeš da pokušaš ponovo sutra.

This is similar to English punctuation in:

• If you don't finish today, you can try again tomorrow.

Yes, Serbian word order is fairly flexible, though some versions sound more natural than others.

The original sentence is very natural:

• Ako ne završiš danas, možeš da pokušaš ponovo sutra.

Possible variations include:

• Ako ne završiš danas, možeš ponovo da pokušaš sutra.
• Ako ne završiš danas, sutra možeš da pokušaš ponovo.

These all mean roughly the same thing, but the position of ponovo and sutra can slightly shift emphasis.

For a learner, the original version is an excellent model to copy.

It can feel like either, depending on context.

• permission: you may try again tomorrow
• possibility: you can try again tomorrow

Without more context, the Serbian sentence can naturally cover both ideas.

That is normal for moći in Serbian, just like can in English often covers more than one meaning.

Sometimes learners expect something like Ako nećeš završiti or Ako ne budeš završio, but that is not the normal everyday pattern for this sentence.

The most natural standard version is:

• Ako ne završiš danas...

Serbian usually prefers this present-tense form after ako for a future condition.
So even though English learners may expect an explicit future form, Serbian does not usually need it here.

Sutra is an adverb meaning tomorrow.

In this sentence, it does not change form. It simply tells you when the action can happen:

• možeš da pokušaš ponovo sutra = you can try again tomorrow

Many time expressions in Serbian work this way as adverbs, without case endings in this use.

Yes. The verb endings show that the sentence is addressed to one person, in the informal singular:

• završiš
• možeš
• pokušaš

If you wanted to say this to several people, or to one person formally, you would use plural/formal verb forms:

• Ako ne završite danas, možete da pokušate ponovo sutra.

So the original sentence is informal singular: you = one person.

Yes — three very useful Serbian patterns appear here:

1. Ako + present for future conditions

   • Ako ne završiš...

2. Perfective verb for a completed result

   • završiti = finish completely

3. Modal + da + present

   • možeš da pokušaš

If you learn those three patterns, you will understand a lot of everyday Serbian sentences built like this one.