The document provides definitions and examples of how to use the modal verbs will, would, and used to. It explains that will is used for present intentions or habits while would is used for past intentions, imagined situations, or habitual actions in the past. Used to is used to talk about repeated events or states that no longer exist. The document gives many examples of how these modal verbs are properly used in different contexts like making requests, offers, predictions, or talking about typical behaviors.