Learn Turkish: İnşaat dün tamamlandı. - The construction was completed yesterday.

The base verb is tamamlamak (to complete). To make it passive, we add the suffix -n, creating tamamlanmak (to be completed). We use -n here instead of -ıl or -ın because the verb stem (tamamla-) ends in a vowel.

Why doesn't inşaat take the accusative case (object) ending here?

In an active sentence (like "They completed the construction"), the construction is the direct object and would take the accusative case (inşaatı). However, in a passive sentence, the thing being acted upon becomes the grammatical subject. Since inşaat is the subject here, it stays in its bare dictionary form.

I recognize the word tamam (OK). How is it built into this verb?

Tamam is an Arabic loanword meaning "complete" (which is why we use it to say "OK"). The suffix -la is commonly used in Turkish to turn nouns or adjectives into verbs, giving us tamamlamak (to complete). Then we add the passive -n and past tense -dı to get tamamlandı (it was completed).

Why is there no personal suffix at the end of tamamlandı?