All compound tenses (such as the
present perfect, the pluperfect, the future perfect, the
conditional perfect, and their subjunctive equivalents) are
composed of two parts: a form of the auxiliary verb haber plus a past participle. Past
participles usually derive from verb infinitives by dropping the
-ar, -er and -ir verb endings and adding the
respective -ado, -ido and -ido endings:
-ar verbs:–> habl + ado = hablado
–> cerr + ado = cerrado
–> despert + ado = despertado-er verbs:
–> com + ido = comido
–> beb + ido = bebido
–> perd + ido = perdido-ir verbs:
–> viv + ido = vivido
–> repet + ido = repetido
–> ped + ido = pedido
The following common verbs and their many variations (e.g. cubrir/descubrir, volver/devolver, have irregular past participles, the forms of which one should memorize:
1. Verbal uses.
Note that the past participle, when used as part of a compound
tense, does not change its form to reflect either the gender or
number of the verb's subject.
Note that the past participle, when used as part of a passive voice construction, agrees in gender and number with the subject of the verb.