ABSTRACT
Most verb forms agree in person and number with the subject of the sentence. However, there are three main verb forms which are impersonal and invariable, i.e. they are not conjugated although some of the verbs they accompany may be. The infinitive – el infinitivo – is the name of the verb. In English it is preceded by ‘to’, as in ‘to sing’, ‘to speak’, ‘to learn’. It is the form used to identify verbs in a dictionary. When the gerund of the auxiliary verb haber appears with the past participle of the main verb it is called a perfect gerund. The past participle also appears in periphrastic constructions. In these cases, the past participle agrees in gender and number with the noun it refers to. There are a number of verbs that have irregular past participles and there is no rule to help learn them.
