* Subject: There isn't a clear subject. We could assume the subject is "you" (implied), but it's not explicitly stated.
* Verb: There is no verb. The sentence is a series of nouns and prepositional phrases:
* "read" - is a verb, but it's being used as a noun (the act of reading).
* "exercise" - is a noun, not a verb.
* "learn" - is a verb, but it's not conjugated (it's missing a tense like "learn" or "learned").
* "about" - is a preposition.
* "Aztec empire" - is a noun.
* "Mexico" - is a noun.
To make this a complete sentence, you could add a verb and a subject:
* Example: "You can read this exercise to learn about the Aztec empire in Mexico."