* Preposition: This is the most common usage. It introduces a phrase that indicates a point in time or an event that marks the beginning of something.
* Example: "I have been living here since 2020."
* Conjunction: It can join clauses, similar to "because" or "as."
* Example: "It's been a long time since we last saw each other."
* Adverb: It can also modify a verb or adjective, indicating a duration of time.
* Example: "She's been gone since yesterday."
It's important to look at the context of the sentence to determine the specific part of speech.