AUGMENT
Any disyllablic verb that begins with a consonant takes an ε in front of the stem in the παρατατικός and αόοριστος of the indicative mood.
This ε is
called an augment (αύξηση). Some
verbs, instead of ε take an η. They are below in the order of
ενεστώδας,
παρατατικός and
αόριστος.
To drink-πίνω, έπινα and
ήπια
To want- θέλω, ήθελα and θελήσα
To find-βρίσκω, έβρισκα and ήβρα
To know-ξέρω, ήξερα (no αόριστος)
Not all the finites in the παρατατικός and αόριστος have an augment. The first and second person plural endings consist of two syllables and hence, the augment is not needed because there already exists a place for the accent.
Any verbs which begin with a vowel or diphthong keep that vowel throughout their conjugation. Exceptions are the following:
To have-έχω, and είχα
To be-είμαι, and ήμουν
When a verb has a prefix the augment also occurs. For example, εκφράζω becomes εξέφραζαν. (The change of this prefix is regular, εκ before consonants and εξ before verbs).