We use the present perfect tense to talk about actions that started in the past and may or may not happen again in the future. To form this tense, we use the auxiliary verb (helping verb) ‘to have’ plus the past participle of the main verb.
have/has (not) + past participle
I have traveled to Italy.
He has talked about this issue more than once.
Have you called your mother this week?
How many times have you called your mother this month?
We haven’t eaten lunch.
She hasn’t written any books.
Why hasn’t he finished his homework?
Forming the past participle
The past participle form of regular verbs can be formed by adding ‘-ed’. There are no rules when forming the past participle form of irregular verbs. These must be memorized. Here is a short list of commonly used irregular verbs.
|Base form||Simple past||Past participle|
You can view a longer list of irregular verbs via The OWL at Perdue Online Writing Lab.