PAST PARTICIPLES

What is a past participle?

A past participle indicates past or completed action or time. It is often called the 'ed' form as it is formed by adding d or ed, to the base form of regular verbs, however it is also formed in various other ways for irregular verbs.
It can be used to form a verb phrase as part of the present perfect tense.
For example:-
I have learnt English. (Learnt is part of the verb phrase 'have learnt')
It can be used to form the passive voice.
For example:-
Her hair was well brushed.
It can also be used as an adjective.

The past participle and the present perfect

Both Spanish and English have perfect tenses that are used to refer to past actions/events/conditions. Both languages use an auxiliary verb (haber in Spanish, to have in English) and a past participle. In English, past

participles are often formed with the endings -ed and -en, for example finished, eaten. You will learn more about Spanish past participles below.

All past participles of -ar verbs end in -ado while past participles of –er and -ir verbs generally end in -ido. If the stem of an -er or -ir verb ends in a vowel, use a written accent on the i of -ido (leer  leído).

Form the present perfect of the indicative by using the present tense of haber as an auxiliary verb with the past participle of the main verb. Tener is never used as the auxiliary verb to form the perfect tense.

Han trabajado mucho para They have worked a lot to...

http://www.englisch-hilfen.de/en/exercises/structures/past_participle.htm

http://www.englisch-hilfen.de/en/exercises/irregular_verbs/crossword_6_7.htm