Most English verbs form their past and past participle forms by adding -ed to the simple present:
accept accepted [has/have/had] accepted
blogblogged [has/have/had] blogged
walk walked [has/have/had] walked
A few verbs form their past and past participle forms in other ways. These are the irregular verbs.
For ease in learning, I have grouped the irregular verbs according to their patterns of forming the past and past participle forms.
NOTE: The past participle form is the form of the verb that is used to form tenses with the helping verbs has, have, and had.
He has lived there for twenty years.
They have tried their best.
I had mistakenly thought that you were finished.
When you wake in the morning, I will have already gone.
one form for simple present, simple past, and past participle. Ex. cut/cut/cut
simple past and past participle spelled the same: Ex.think/thought/thought
past participle different from simple past: Ex. begin/began/begun
The verbs in this group are a mixed bag. Some are in transition between regular and irregular, so -ed forms exist side by side with irregular forms. For example: mowed/mowed/mown; dive/dove/dived.
Others seem to have taken on one meaning for the irregular form and another for the regularized form. For example, a novelist might use the word bid to mean “command or request”
Lady Ashcroft bade the servant shut the drapes. The servant did as he was bidden.
A modern bridge player, however, would say
Margie just bid four hearts, and now June has bid three hearts.