Phase verbs locate an action at its boundary: почети opens it, наставити resumes or maintains it, and престати closes it. Their complement must name an activity with internal duration, so it is normally imperfective: почети да пише, наставити читати, престати пушити.
There are two aspect choices in every such construction. The phase verb chooses its own perfective or imperfective partner, while the governed activity remains imperfective. English start to write hides that division because the English infinitive has no aspect. For the general process-versus-boundary contrast behind these choices, see Verbal Aspect: The Big Picture.
Two Layers of Aspect
| Bounded phase verb | Imperfective partner | Meaning |
|---|---|---|
| почети | почињати | begin once / begin habitually or gradually |
| престати | престајати | stop once / repeatedly or gradually stop |
| наставити | настављати | resume or continue once / do so repeatedly |
Почео сам да радим у осам.
I started working at eight. (male speaker; one bounded beginning)
Током лета почињем да радим раније.
During the summer I start working earlier. (habitual pattern)
Perfective почео сам views one onset as a whole. Imperfective почињем can present a repeated schedule or the beginning as an unfolding process. In both, imperfective радити supplies the activity entered.
The Complement Is Imperfective
A phase verb selects a process, not an already packaged result. That is why Serbian normally requires the imperfective member of an aspect pair after почети, престати, наставити.
Марија је почела да пише одговор, али га још није завршила.
Marija started writing the reply, but she has not finished it yet.
Престани да провераваш телефон док возиш.
Stop checking your phone while driving.
После кратке паузе наставили смо да разговарамо.
After a short break, we continued talking.
The complements писати, проверавати, разговарати are imperfective. Perfective написати or проверити presents reaching an endpoint and therefore clashes with the meaning begin/stop/continue the process.
да + Present and the Infinitive
Contemporary standard Serbian permits both complement types when the subject is shared.
Почела је да учи српски прошле јесени.
She started learning Serbian last fall.
Почела је учити српски прошле јесени.
She started learning Serbian last fall.
The finite да construction is especially frequent in everyday Serbian. The infinitive is also standard and occurs readily in writing and in many speakers’ usage. Neither construction changes the aspect rule: учи / учити is imperfective in both.
Because a bare infinitive has no subject of its own, a phase construction normally has subject control: the person who begins is also the person who performs the embedded activity. For a separately stated actor, restructure the sentence rather than copying an English object-plus-infinitive pattern.
Директор је најавио да ће тим почети да ради у понедељак.
The director announced that the team would start working on Monday.
Here тим is the subject of finite ће почети. It is not an object inserted before an infinitive.
Compact Forms and Agreement
The present of perfective почети is useful in future-oriented subordinate clauses; ordinary present-time repeated beginnings use почињати.
| Person | почети | престати | наставити |
|---|---|---|---|
| ја | почнем | престанем | наставим |
| ти | почнеш | престанеш | наставиш |
| он / она / оно | почне | престане | настави |
| ми | почнемо | престанемо | наставимо |
| ви | почнете | престанете | наставите |
| они / оне / она | почну | престану | наставе |
Кад почнемо да снимамо, искључите телефоне.
When we start recording, turn off your phones.
In the past and conditional, the l-participle agrees with the phase verb’s subject.
Почела бих да тренирам поново, али ме још боли колено.
I would start training again, but my knee still hurts. (female speaker)
Гости су престали да разговарају чим је музика почела.
The guests stopped talking as soon as the music started.
In a neutral perfect clause, auxiliary clitics occupy second position: Марија је почела, После паузе смо наставили. The complement’s clitics belong inside its own finite да-clause: почео је да га чита, not a mechanically copied English order.
Affirmative, Negative, and Question
Настављамо да радимо после ручка.
We are continuing work after lunch.
Не настављамо да радимо док не добијемо дозволу.
We are not continuing work until we receive permission.
Да ли настављамо да радимо после ручка?
Are we continuing work after lunch?
Regular не precedes the finite phase verb. In a да ли question, the phase verb remains fully inflected; Serbian does not insert an equivalent of English do.
Noun Complements and Their Cases
The three verbs also take nominal complements, but not with identical government.
Почети and престати commonly take с/са + instrumental when the complement is an activity treated as a named undertaking or habit.
Почели смо с обновом кухиње прошлог месеца.
We began renovating the kitchen last month.
Престао је с пушењем после двадесет година.
He gave up smoking after twenty years.
Наставити readily takes an accusative direct object, and can also use са + instrumental when the emphasis is on proceeding with something already established.
После паузе наставили смо разговор у ходнику.
After the break, we continued the conversation in the hallway.
Можемо наставити са следећом тачком дневног реда.
We can continue with the next item on the agenda.
The noun pattern can sound more institutional or programmatic: почети с применом новог система is natural in formal administrative prose. A verbal complement foregrounds the action: почети да примењујемо нови систем.
Stop Doing versus Stop in Order to Do
English stop has two structures. Serbian makes the difference explicit.
Престао је да пије кафу.
He stopped drinking coffee; he gave up the habit.
Застао је да попије кафу.
He stopped what he was doing in order to have a coffee.
Престати + imperfective complement terminates the embedded activity. Застати да + perfective means pause in order to perform another bounded action. Treating both English sentences as престати erases the purpose reading.
Resume, Keep Going, or Extend
Наставити can mean resume after an interruption or keep an action going. Context supplies the difference.
Кад се веза вратила, наставила је да објашњава проблем.
When the connection returned, she resumed explaining the problem.
Иако је било касно, наставили су да славе.
Although it was late, they kept celebrating.
With a spatial or organizational object, наставити can also mean extend or carry on something, which is not a phase complement: наставити пут (continue the journey). That direct-object use does not create an infinitive aspect rule because there is no embedded verb.
Practice Tasks
Task 1: Choose Both Aspects
Describe one bounded beginning of an ongoing writing process, then a recurring beginning.
Јуче сам почео да пишем извештај; иначе почињем да га пишем тек после ручка.
Yesterday I started writing the report; normally I start writing it only after lunch. Answer: perfective почео for one onset, imperfective почињем for repetition, imperfective пишем in both complements. (male speaker)
Task 2: Choose Verbal or Nominal Government
Express giving up smoking first with a clause, then with a noun.
Престала је да пуши. Престала је с пушењем.
She stopped smoking. She gave up smoking. Answer: imperfective пуши after да; instrumental пушењем after с.
Common Mistakes
Putting a perfective complement after a phase verb
❌ Почео сам да напишем жалбу.
Incorrect for beginning the activity—perfective напишем packages the result instead of naming the process.
✅ Почео сам да пишем жалбу.
I began writing the complaint. (male speaker)
Changing aspect only because the phase verb changes
❌ Сваког дана почињем да прочитам пошту у девет.
Incorrect—the repeated phase verb is imperfective, but its reading activity must also be imperfective читам.
✅ Сваког дана почињем да читам пошту у девет.
Every day I start reading my mail at nine.
Copying English stop to do with престати
❌ Престао је да попије воду, па је наставио да трчи.
Incorrect for a purposeful pause—престати means cease the embedded activity.
✅ Застао је да попије воду, па је наставио да трчи.
He stopped to drink some water, then continued running.
Omitting the preposition before a nominal complement
❌ Престала је пушењем прошле године.
Incorrect government—the instrumental activity noun requires с.
✅ Престала је с пушењем прошле године.
She gave up smoking last year.
Misplacing the perfect auxiliary
❌ После паузе наставили да радимо смо.
Incorrect—the auxiliary смо cannot be stranded after the complement clause.
✅ После паузе смо наставили да радимо.
After the break, we continued working.
Key Takeaways
- Почети, престати, наставити identify a boundary or continuation within an activity.
- The phase verb chooses its own aspect; its verbal complement is normally imperfective.
- Both the infinitive and same-subject да + present are standard, with the finite pattern especially common in speech.
- Почети/престати с + instrumental name an undertaking or habit; наставити also takes an accusative direct object.
- Престати да пије means stop drinking; застати да попије means pause in order to drink.
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Start learning Serbian →Related Topics
- The InfinitiveA1 — The -ti/-ci citation form and its uses.
- da + present vs the InfinitiveB1 — When to use the infinitive and when da + present.
- Verbal Nouns (-nje)B1 — Deriving action nouns from verbs and their syntax.
- počinjati / početi (to begin)B2 — Beginning, a phase verb.
- Verbal Aspect: The Big PictureA2 — Why nearly every verb comes in an imperfective/perfective pair.