Italian B2: If I had known: the third conditional · Words

For what did not happen: se + congiuntivo trapassato (avessi or fossi + participle), then the past conditional (avrei or sarei + participle): Se avessi saputo, sarei venuto. The past conditional also gives a future seen from the past: Ha detto che sarebbe arrivato alle otto. In casual speech you will also hear the imperfetto in both halves: Se lo sapevo, venivo.