When to use a comma before "just":
* When "just" is an introductory word: This is similar to using a comma with other introductory words like "however", "therefore", or "finally".
* Example: Just as I was leaving, the phone rang.
* When "just" is used as an interjection: This is a more informal usage, and it's often used to express surprise or emphasis.
* Example: I finished the project, just like that!
When NOT to use a comma before "just":
* When "just" is an adverb modifying a verb: In this case, "just" is part of the verb phrase and doesn't require a comma.
* Example: I just finished my work.
* When "just" is part of a prepositional phrase:
* Example: I went to the store just for milk.
Key point: The function of "just" in the sentence determines whether or not you need a comma before it. Think about what "just" is doing in the sentence to make the correct decision.