Except for the verb be, all main verbs in English have five forms. The following list shows the five forms for the regular verb walk and the irregular verb ride.
Base form: walk, ride
Past tense: walked, rode
Past participle: walked, ridden
Present participle: walking, riding
-s form: walks, rides
For regular verbs, both the past-tense and past-participle forms end in -ed or -d: walked, walked. For irregular verbs, the past tense and past participle are formed differently for each verb: rode, ridden; began, begun.
Common irregular verbs
Exercises:
Irregular verbs 1
Irregular verbs 2
Irregular verbs 3