You are look at the page for irregular verb buy
The present perfect tense is a combination of the present tense and perfect aspect that expresses an event in the past with consequences in the present.
For this tense we use auxiliary verbs in their base form in combination with main verbs in their past participle form. This tense is quite easy to learn but harder to use in practice, but nonetheless it’s a tense we must know. To properly construct sentences, we have to learn all the irregular verbs and know their forms.Read more