Here's why:
* Participial Phrase: A participial phrase is a group of words that functions as an adjective and includes a participle (a verb form ending in -ing or -ed).
* In this case: "working" is the present participle of the verb "to work" and it modifies the noun (or pronoun) it refers to.
Example:
* The woman working so hard is my sister. ("working so hard" modifies "woman")
Let me know if you'd like to explore other types of phrases!