Final answer:
The most irregular verb in English is 'to be.' Unlike regular verbs that form the past tense and past participle by adding -ed, the past forms of 'to be' include am, is, are, was, were, and been.
Step-by-step explanation:
Irregular verbs are a key part of the English language and learning them is essential for achieving verb tense consistency when speaking or writing. The most irregular verb in English is to be. Unlike regular verbs that form the past tense by adding -ed or -d, irregular verbs have unique past tense and past participle forms. For example, the verb to walk is a regular verb because its past tense is walked, and the past participle is also walked. Conversely, to be is highly irregular; its forms include am, is, are (present), was, were (past tense), and been (past participle). Another example is the verb to see, which has the past tense saw and the past participle seen.