In this sentence All of the tables are set all is subject. Is that because a pronoun?

You're right! In the sentence "All of the tables are set", "all" is the subject. And yes, it's a pronoun because it stands in for a noun phrase (the tables).

Here's why:

* Pronoun: A pronoun replaces a noun or noun phrase to avoid repetition. In this case, "all" replaces "the tables."

* Subject: The subject of a sentence performs the action or is the one being described. Here, "all" (representing the tables) are being described as "set."

Let me know if you have any other grammar questions!