Here's why:
* Subject pronouns are used when the pronoun is the subject of a sentence or clause. They perform the action of the verb.
* Example: We went to the park. (We is the subject, performing the action of going)
* Object pronouns are used when the pronoun is the object of a verb or preposition. They receive the action.
* Example: The dog chased us. (Us is the object, receiving the action of chasing)
Let me know if you have any other pronoun questions!