Rules for writers, Tenth edition - Diana Hacker, Nancy Sommers 2021

Choose correct forms of irregular verbs
Choose appropriate verb forms, tenses, and moods
Grammar

Except for the verb be, all verbs in English have five forms. The following list shows the five forms and provides a sample sentence in which each might appear.

The verb be has eight forms instead of the usual five: be, am, is, are, was, were, being, been.

27a Choose correct forms of irregular verbs.

For all regular verbs, the past-tense and past-participle forms are the same (ending in -ed or -d), so there is no danger of confusion. This is not true, however, for irregular verbs, such as the following.

The past-tense form always occurs alone, without a helping verb. It expresses action that occurred entirely in the past: I rode to work yesterday. I walked to work last Tuesday. The past participle is used with a helping verb. It forms the perfect tenses with has, have, or had; it forms the passive voice with be, am, is, are, was, were, being, or been. (See 47c for a complete list of helping verbs and 27f for a survey of tenses.)

The list of common irregular verbs below will help you distinguish between the past tense and the past participle. Choose the past-participle form if the verb in your sentence requires a helping verb; choose the past-tense form if the verb does not require a helping verb. (See verb tenses in 27f.)

Common irregular verbs