This document discusses the usage of four English verb tenses: the present perfect, past perfect, present perfect continuous, and future perfect continuous. For each tense, it provides the affirmative, negative, and interrogative forms using the verbs "buy", "have", and "speak" as examples. It explains that the present perfect is used for past actions connected to the present, the past perfect establishes order between past actions, the present perfect continuous expresses ongoing actions reaching the present, and the future perfect continuous expresses how long an action will have lasted at a future point.