present perfect

•The present perfect is one of the eight basic English verb tenses. It is formed as follows:

auxiliary: present tense of "have" + main verb: past participle

•The present perfect is used in four important ways:

1.  to refer to a "state" (in other words, a condition or situation) that begins in the past and continues up to the present
2.  to refer to an event that occurs at some indefinite time in the past