PARTICIPLES
In Greek, verbs have three voices: active, passive and reflexive voices. The
active voice forms an indeclinable participle, while the passive voice forms
participles, which are declinable. The reflexive voice uses the active
participle. Usually verbs have a participle in both voices; even if they exist
in one elsewhere. The active participle is made from the present stem plus
"οντας."
The passive participle is made from the aorist stem plus "μέωος." This participle also behaves like an
adjective. For example:
τρώγω (to eat) τρώγω καλά. (I eat well)
τρώγοντας (while eating) τρώγοντας πνίγηκα. (While eating I choked). This participle can only be used this way. It is always accompanied by another verb, which shows the voice, tense, person and number.
φαγωμένος (eaten) είδα το ψωμί μου φαγωμένο (I saw my bread eaten). Another example is το φαγωμένο ψωμί (the eaten bread). In both examples, this participle only acts like an adjective.
Φάγει and φαγωθεί are the past participles for the perfect tense and come from the verbs τρώγω and τρώγομαι respectively. The only difference is that one is in the active voice and the other in the passive voice. Therefore έχω φάγει means I have eaten and έχω φαγωθεί means I have been eaten.
All past participles, which are used in the perfect tenses, are made in a regular way, irrespective of voice. One isolates the past stem (the stem could be irregular) and always adds ->ει to the ending, irrespective of conjugation. For the above examples, the past stem is irregular. From the present stem -τρωγ- the past stem φαγ- is made-in the active voice.