The main verbs, which derive their past and past participle forms by undergoing a change in their constituent vowels such that two or all the three forms are dissimilar, are called Strong or Irregular Verbs.
Examples:
| V1 Base Form |
V2 Past Simple |
V3 Past Participle |
| awake | awoke | awoken |
| begin | began | begun |
| choose | chose | chosen |
| dig | dug | dug |
| eat | ate | eaten |
| fall | fell | fallen |
| go | went | gone |
| have | had | had |
| know | knew | known |
| lay | laid | laid |
| make | made | made |
| pay | paid | paid |
| read | read | read |
| say | said | said |
| take | took | taken |
| understand | understood | understood |
| wake | woke | woken |