The document provides information about learning and using the past perfect tense, including its forms, uses, examples, and clues. It discusses the positive and negative forms of the past perfect, example questions in the past perfect, the difference between tag and information questions, and provides extra practice with coming up with your own examples. It also clearly explains that the single use of the past perfect is to refer to an earlier completed action that took place before another past action. Several examples are given to illustrate this use. Time expressions that can indicate the past perfect tense are also listed.