Verbs that are formed in ways other than through the use of the suffix –ed are
considered to be irregular. Some of these verbs add suffixes –d or –t similar to regular
past tense verb forms. Many others are formed through changes in the vowels of the
verbs. Some of them have a zero suffix and do not change at all. While there are some
general patterns for the irregular past tense forms, the number of variations is greatly
varied and not easily predicted.
For the past participle forms, there are also various ways other than the affix –
ed. These irregular forms have many variations. Although there are some general
patterns, this aspect of inflection is also highly irregular and unpredictable. Also,
some past participles have two accepted forms, regular and irregular.