Forming Active-Passive Verbs in Spanish
I currently dug up an old notebook from College (1996) and found this entry on converting singular active verb to past, future, passive by adding suffixes/prefixes.
E.g.
es comprado -- present
fue comprado -- past
era comprado -- present perfect
sera comprado -- future
ha sido comprado -- have been
habia sido comprado-- had been
habra sido comprado--will have been

