Some past participles are irregular. For example ... The first part of the perfect tense is the present tense of the verb haber, which is known as an auxiliary verb. An auxiliary verb, also ...

Go to: weak verbs in '-d' and weak verbs formed with -t. There is one verb that is irregular and weak in the past tense, but strong in the the non-progressive participle: do, did, done. A few verbs ...