The verb dr ive, for example, changes to dr ove in the past tense. With the irregular past tense, it is common for a vowel in the middle of the verb to change instead of the verb's ending. Let's take a closer look at how the irregular past tense and past participles are formed. You'll learn more about this concept later in this lesson. Most irregular verbs follow a specific pattern.Beg an (base form, beg in) and fr oze (base form, fr eeze) are a two good examples. It's very common for a vowel (or pair of vowels) to be different from the base form.Some examples are at e, fough t, swa m, and give n. They all have one important characteristic in common: they almost never end in -ed.Here are a few basics you'll want to remember about the irregular past tense and past participle forms. Irregular Past Tense and Past Participles