When we portray about the subjunctive, imperative and nominal forms, these indicate some peculiarities that guide the grammatical class represented by verbs. And speaking of them, we know they are not few.
Going further, we find that such elements refer to one of the verbal forms – that of auxiliaries. In this sense, it is worth remembering that they do not exist by themselves, since they are part of those compound forms, formed by a main verb - bringing with them the greater semantic load, and also by the auxiliary verbs themselves, whose characteristic is to demarcate the tense, mode, number and person from the main form.
Thus, this article aims to highlight the way in which the auxiliaries are conjugated, in view of the modes, subjunctive, imperative and nominal forms. Watch:
subjunctive mode
Gift
Imperfect past tense 
Future
Imperative mode
Affirmative
Negative
Nominal Forms
impersonal infinitive
Personal infinitive
Gerund
Participle
By Vânia Duarte
Graduated in Letters
Brazil School Team
Source:
Brazil School - https://brasilescola.uol.com.br/gramatica/subjuntivo-imperativo-formas-nominais-dos-auxiliares.htm