2nd person singular and plural perfect indicative for perfect stems ending in āv, ēv, īv, and ōv: vi is omitted, e.g.
+laudavisti → laudasti,
+laudavistis → laudastis,
+requievisti(s) → requiesti(s),
+audivisti(s) → audisti(s),
cognovisti(s) → cognosti(s)
2nd person singular and plural perfect indicative for perfect stems ending in āv, ēv, īv, and ōv: vi is omitted, e.g.
+laudavisti → laudasti,
+laudavistis → laudastis,
+requievisti(s) → requiesti(s),
+audivisti(s) → audisti(s),
cognovisti(s) → cognosti(s)