The way a verb forms its past tense determines its classification as regular or irregular. A regular verb takes the –d or –ed ending to denote the past tense.

Irregular verbs do not take the –d or –ed ending. They are inflected in various other ways to indicate past tense.

Regularbelieve → believedsmile → smiled

Irregularrun → raneat → ate

An irregular verb forms its past and past participle by

changing vowels (run-- ran) or consonants (build– built)

or by changing vowels and consonants (catch – caught)

or by making no changes (burst, cost)

Every verb has four basic parts, which are called its principal parts. You must know all of these in order to form the different tenses correctly.

Present (aka Infinitive)PastPresent ParticiplePast Participle

existing or happening now

know to knowtake to takewrite to write

existed or happened in the past

knewtookwrote

The present participle of a verb always ends in –ing.

knowingtakingwriting

The past participle of a verb always requires a helping verb (have, has, had).

had knownhave takenhas written

Present Past Past Participle

begin 1. __________ have begun

freeze 2. __________ have frozen

write wrote 3. _________

blow 4. __________ have blown

drive drove 5. _________

wear wore 6. _________

sing 7. __________ have sung

ride 8. __________ have ridden

Present Past Past Participle

begin 1. have begun

freeze 2. have frozen

write wrote 3.

blow 4. have blown

drive drove 5.

wear wore 6.

sing 7. have sung

ride 8. have ridden

Present Past Past

Participle

choose chose 9. _________go 10. _________ have gonerun 11. _________ have runthrow threw 12. ________come came 13. ________see saw 14. ________speak 15. _________ have spokenburst 16. _________ have burst

Present Past Past Participle

choose chose 9. go 10. have

gonerun 11. have runthrow threw 12. come came 13. see saw 14. speak 15. have spokenburst 16. have

burst

Present Past Past Participle

swim swam 17. ________

sink sank 18. ________break 19. _________ have brokenbring 20. _________ have brought

Present Past Past

Participle

swim swam 17. sink sank 18. break 19. have brokenbring 20. have brought