>You were supposed to leave 2 days ago.
>
>Jak dla mnie pierwsze zdanie to zgroza.
You were supposed to leave/to have left 2 days ago. - oba odnosza sie do tego samego, czyli do przeszlosci z racji tego, iz jest tam w zdaniu 'two days ago'.
gdyby nie ten okolicznik czasu, wowczas TYLKO zdanie z 'perfect infinitive' daje nam absolutna jasnosc, iz zdanie dotyczy przeszlosci; taka to wlasnie roznica:
You were supposed to leave. (przeszlosc lub przyszlosc w przeszlosci)
You were supposed to have left. (przeszlosc)
You were supposed to leave/to have left two days ago. (przeszlosc)
You were supposed to leave the next week. (przyszlosc w przeszlosc)
You were supposed to have left the next week. (przeszlosc, z odniesieniem sie do jakiegos nastepnego tygodnia w przeszlosci)