Picture of Christophe Grandsire-Koevoets
Re: Past tense / perfective of passive verbs
by Christophe Grandsire-Koevoets - Thursday, 17 December 2009, 09:58 AM
  To know a verb in Greek, one has to learn to so-called "principal parts". Once you know these, you are supposedly able to derive everything else. Those parts are traditionally:
- the first person singular indicative present active (which gives you the active imperfective stem). Make a habit of learning it with the -άω ending when valid and you will immediately know whether the verb has an -άς or -είς conjugation type.
- the first person singular indicative aorist active (which gives you the active perfective stem).
- the first person singular indicative aorist passive (which gives you the passive perfective stem).
- the perfective participle (which is mostly used as an adjective).
But indeed, for many verbs it's not quite enough unless you know by heart all the available patterns. So to those I usually add the following:
- the first person singular indicative present passive (so that I know which passive endings are used in the present).
- the first person singular indicative imperfect passive (for the same reason).
- the first person singular subjunctive perfective active (when it's not exactly the same stem as the aorist).
- the first person singular subjunctive perfective passive (for the same reason).
- the second person singular perfective imperative, both active and passive (those are not always directly inferable from the aorist).

With all these, I usually can conjugate any verb to any voice-aspect-tense-mood combination, whether they are regular or irregular.