* Adverb: This is the most common use of "so." It expresses degree or intensity, often used to emphasize something.
* Example: "The movie was so good!"
* Conjunction: It can connect clauses, showing a result or consequence.
* Example: "She was tired, so she went to bed early."
* Pronoun: It can replace a noun phrase, usually referring to something previously mentioned.
* Example: "I asked for a sandwich, and so she brought me one."
* Interjection: It can express surprise or agreement.
* Example: "So, you're going to the party?"
To determine the part of speech of "so" in a particular sentence, consider its function and the words around it.