The pretérito pluscuamperfecto de subjuntivo is formed by the auxiliar verb "haber" in the past subjunctive tense followed by the past participle of the main verb. The English equivalent of the pretérito pluscuamperfecto de subjuntivo could be, depending on the situation, the past perfect "had + past participle of the main verb ", the conditional perfect "would or could + have + past participle of the main verb” or, simply, a past tense when the sentence has a subjunctive nuance.