Regular and irregular verbs
§ 6. Owing to the historical development of the verb system the English verbs fall into two groups: regular and irregular verbs.
The regular verbs, which go back to the Germanic weak verbs, constitute the largest group. The past indefinite and participle II of these verbs are formed by means of the dental suffix -ed added to the stem of the verb. This is the productive pattern according to which all new verbs form their past indefinite and participle II.
The irregular verbs form their past indefinite and participle II according tо some fixed traditional patterns going back partly to the Germanic strong verbs, partly to the weak verbs, which underwent some changes in the process of history.
The irregular verbs are about 250 in number. They can be arranged according to sound changes.
The list of irregular verbs arranged according to sound changes