Final answer:
In the sentence provided, "copies" is the simple subject and "are worth" is the simple predicate. These components are critical for understanding sentence structure and ensuring subject/verb agreement.
Step-by-step explanation:
In the sentence "Wow, copies of a first run Philosopher's Stone book are worth over $40,000!", the simple subject is "copies" and the simple predicate or verb is "are worth". The simple subject is the main noun that the sentence is about, while the simple predicate consists of the verb or verb phrase that tells us something about the subject. In this case, the simple predicate includes a helping verb (are) paired with the main verb (worth) to convey what is predicated about the copies of the book.
Understanding the concept of subject and predicate is essential for grasping sentence structure. The subject and verb in a sentence must agree in number, and prepositional phrases must not be confused as the subject. It is important to identify properly to maintain subject/verb agreement and to ensure that sentences are clear and grammatically correct.