This document discusses linking verbs and the verb "to be". It explains that linking verbs describe a state of being or change rather than an action. "To be" is one of the most common verbs in English and is used to form tenses. Linking verbs connect the subject of a sentence to a subject complement that provides additional information about the subject. For example, in the sentence "The dog was really fierce", the linking verb "was" connects the subject "dog" to the adjective complement "fierce".