The Sentence Diagram Generator visually represents the grammatical structure of the sentence "An extremely unusual program won't be broadcast tonight." Here is a breakdown of the diagram:

1. Subject: "program"

   • Modifier: "An"
   • Modifier: "extremely"
   • Modifier: "unusual"

2. Predicate: "won't be broadcast tonight"

   • Auxiliary Verb: "won't"
   • Main Verb: "be"
   • Past Participle: "broadcast"
   • Adverbial Modifier: "tonight"

This structure illustrates the relationships between the components of the sentence, highlighting the subject and its modifiers, as well as the predicate and its elements.