The document summarizes the rules and usage of the present perfect tense in English. It discusses:
1) How to form the present perfect tense using has/have + past participle. It provides examples of affirmative and interrogative sentences.
2) The two main uses of the present perfect tense: to refer to an unspecified time in the past with relevance to the present, and to describe situations that began in the past and continue in the present.
3) Time expressions that are commonly used with the present perfect tense, including ever, already, yet, so far, today, this week, etc.
4) An exercise section tests the reader's understanding of forming and using the present perfect tense