The past: radio sam, not a bare radio

English "I worked" is one word. Serbian needs two: an -o / -la participle and a helper from the verb "to be" — the same machinery as English "I have worked", except the helper changes with the person. Radio sam, radila sam, radili smo. Without the helper the phrase sounds cut off — like "worked" without the "I". For example: “Јуче сам био код лекара” — Yesterday I was at the doctor's. A rule from the Serbian course…

Updated September 1, 2026 · Lingofly

How it works

English "I worked" is one word. Serbian needs two: an -o / -la participle and a helper from the verb "to be" — the same machinery as English "I have worked", except the helper changes with the person. Radio sam, radila sam, radili smo. Without the helper the phrase sounds cut off — like "worked" without the "I".

The masculine participle ends in -o (easy to remember: it looks like the English word radio): radio, išao, izgubio. The feminine puts the l back: radila, išla, izgubila. So the Serbian past always betrays the speaker: a man says izgubio sam pasoš, a woman izgubila sam pasoš — "I lost my passport" hides it completely.

The helper is a clitic and sits in the same second position as sam and se: it cannot open the sentence. Juče sam radio, never "Sam juče radio" — just as an English contraction cannot: "'D worked yesterday" is not English.

Two exceptions you will hit at once. In the third person the helper je, and next to se it vanishes: not "pokvarilo se je" but simply pokvarilo se. And negation is one fused word: nisam radio, nije došao.

Table

The past: radio sam, not a bare radio
whothe helperexample
ja (m)samradio sam — I worked (a man speaking)
ja (f)samradila sam — I worked (a woman speaking)
tisiradio si — you worked
on / onajeradio je / radila je — he / she worked
mismoradili smo — we worked
visteradili ste — you (pl.) worked
onisuradili su — they worked
negationnisam, nisi, nije…nisam radio — I did not work

By example

  • Јуче сам био код лекара
    Juče sam bio kod lekara
    Yesterday I was at the doctor's
  • Нисмо добили рачун
    Nismo dobili račun
    We did not get the bill
  • Лифт се покварио прошле недеље
    Lift se pokvario prošle nedelje
    The elevator broke last week

How the rule settles in your head

A rule is not memorized from an explanation. It is memorized from an attempt to use it and a mistake — that is why the app delivers it mixed in with words, not as a separate lesson: it resurfaces exactly where you forgot it.

Frequently asked

The past: how does it work in Serbian?

English "I worked" is one word. Serbian needs two: an -o / -la participle and a helper from the verb "to be" — the same machinery as English "I have worked", except the helper changes with the person. Radio sam, radila sam, radili smo. Without the helper the phrase sounds cut off — like "worked"…

What does it look like in an example sentence Serbian?

“Јуче сам био код лекара” (Juče sam bio kod lekara) — Yesterday I was at the doctor's. A rule is easier to test on sentences like this than to memorize as a wording: what surfaces in conversation is the sentence.

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