The basic forms of the verb in Modern English are: the Infinitive, the Past Indefinite, and Participle II. According to the way in which the Past Indefinite and Participle II are formed, verbs are divided into three groups: regular verbs, irregular verbs, and mixed verbs. Regular Verbs Regular verbs form the Past Indefinite and Participle II by adding - ed to the stem of the verb, or only - d if the stem of the verb ends in - e. to want — wanted to open — opened to unite — united to live — [...]