This document discusses the key parts of a sentence: the subject, which is the part about which something is said, and the predicate, which says something about the subject. It notes that every sentence has a subject and predicate. It further breaks down sentences into their simple subject (the main word in the subject) and simple predicate or verb (the main word or group of words in the predicate). The complete subject includes the simple subject and any modifiers, while the complete predicate includes the simple predicate and any modifiers.