The document discusses the use of the construction "used to" to talk about past habits, repeated actions, or things that were previously true but are no longer the case. It provides examples of using "used to" in affirmative, negative, and question forms. The document also explains when to use "be used to" to talk about things that are currently habitual or normal for someone. Exercises are included to practice using "used to" and "be used to" correctly.