Answer:
An auxiliary verb (or a helping verb as it's also called) is used with a main verb to help express the main verb's tense, mood, or voice.
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1)They appear in the following forms:
2)To Be: am, is, are, was, were, being, been, will be.
3)To Have: has, have, had, having, will have.
4)To Do: does, do, did, will do.