Is “was” a helping verb?

Was,” like other forms of “be,” can either be a main verb or a helping verb (aka auxiliary verb). As a main verb, “be” is always a stative and linking verb (e.g., “I was a doctor”). As a helping verb, it helps to form the passive voice (e.g., “the house was sold”) and progressive tenses, such as the present progressive (e.g., “I was selling my house”).