What type of pronoun This is the first book?

The sentence "This is the first book" doesn't contain a pronoun. It contains the demonstrative adjective "this".

Here's why:

* Pronouns replace nouns (e.g., he, she, it, they, you).

* Demonstrative adjectives point to specific things (e.g., this, that, these, those).

In this sentence, "this" modifies the noun "book" to indicate a specific book, making it a demonstrative adjective.