We form the perfect tenses by using the verb *to have* as an auxiliary verb and adding the past participle of the main verb. For example we form the present-perfect tense by using the present tense of have (has or have) and adding the past participle of the main verb.
Those helping verbs are named *auxiliary verbs* . And the common ones are to be, to have, and to do. They appear in the following forms:
To Be: am, is, are, was, were, being, been, will be
To Have: has, have, had, having, will have
To Do: does, do, did, will do
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Explanation:
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