ero certo

I was sure

→ essere
phrase Common #4,403
I was sure The phrase changes with the subject and tense: sono certo/ certa means “I am sure,” while ero certo/ certa means “I was sure.”
IT: Ero certo che sarebbe arrivato in tempo.
EN: I was sure he would arrive on time.

Ero certo che sarei riuscito a dimenticare.

I was sure I could forget.

— Malèna (2000)

Ma di una cosa ero certo.

But of one thing I was certain.

— Happy Together (1997)

Io ero certo che non voleva gareggiare.

I was sure he didn't want to compete.

— Senna (2010)

Ero certo che sarei arrivato da qualche parte.

I was certain that I would get somewhere.

— Barfi! (2012)

Ne ero certo.

I was sure of it.

— Eternity (2025)

Ero certo del percorso da seguire.

I was sure of the path to follow.

Ero certo che avresti fatto grandi cose.

I was certain that you would do great things.

— 3 Idiots (2009)

Ne ero certo!

I was certain of it!

— La spina del diavolo (2001)