Breakdown of Dok sam čitao knjigu, on je stalno pričao.
biti
to be (sam, si, je)
on
he
knjiga
book
čitati
to read
Questions & Answers about Dok sam čitao knjigu, on je stalno pričao.
Why are both čitao and pričao imperfective verbs here?
Both actions were continuous and happening at the same time in the past (was reading, was talking). Imperfective verbs are used for ongoing processes. The word dok (while) often signals that you will need an imperfective verb.
Why is there no ja (I) before sam čitao, but on (he) is included later?
In Croatian, subject pronouns like ja are usually dropped because the auxiliary verb (sam) already shows who the subject is. However, on is included to create a strong contrast between the two people: I was doing this, while he was doing that.
Why does sam come directly after Dok?
The verb sam is an enclitic, which means it is a weak word that must take the second position in its clause. Since Dok is the first word, sam automatically takes the spot right next to it.
Could I say on stalno je pričao instead of on je stalno pričao?
No, because je is an enclitic. It must take the second position in the clause, immediately after the first word (on). The adverb stalno (constantly) naturally goes right before the main verb (pričao).