Uses of Auxiliary Verb 'Be' in English Grammar. Verb 'Be' used as an action verb and stands alone in all tenses. It is equal to Am, Is and Are, They are called BE forms, but Be can not replace them. auxiliary verb be, be as an action verb, be able to talk about ability, sentences with verb be https://www.englishmirror.com/english-grammar/auxiliary-verb-be.html