| HAD + PAST PARTICIPLE
(simple past of be + pa.pa.)
|I had finished lunch when he visited me
You had answered before I even asked you..
She had had cleared the table when I came in.
They left the building as soon as they had heard the fire alarm.
past participle of regular verbs
past participle = infinitive + ED
special: drop the end -E of the infinitive
invite -> invited
past participle of irregular verbs
Irregular means that they don't follow rules.