The present perfect tense of the verb ‘attend’ is ‘have attended’ or ‘has attended’.
This tense is used to describe actions that occurred at some indefinite point in the past but are relevant to the present moment. For example, you might say, ‘I have attended three conferences this year.’ This indicates that your attendance at these conferences is significant to your current situation.
In this structure, ‘have’ is used with the subjects ‘I’, ‘you’, ‘we’, and ‘they’, while ‘has’ is used with ‘he’, ‘she’, and ‘it’. The past participle of ‘attend’ is ‘attended’, which is used in both cases.