When is ε added as a prefix in the simple past?

Answer 1

When we create the past for verbs in the active voice, we move the accent one syllable to the left, towards the beginning of the word, so that it falls on the 3rd last syllable (πληρώνω --> πλήρωσα). If we don't have enough syllables in order to do so, we add the letter "ε" and we place the accent over it (λύνω --> έλυσα).

Please note: there are some exceptions.