The document discusses the three main uses of the future perfect tense: 1) to talk about actions that will be completed before a specified time in the future, 2) to talk about actions that will continue into the future past a given point, and 3) to express certainty that something occurred in the recent past. Common time expressions used with the future perfect include "by", "by the time", "before", and references to specific future times. Examples are provided to illustrate the formation and use of positive sentences, questions, and negative sentences in the future perfect tense.