Pronouns used as the subject of a sentence need to be in the nominative case.
Here's a breakdown:
* Subject: The person or thing performing the action in a sentence.
* Nominative case: The form of a pronoun used when it's the subject of a sentence.
* Objective case: The form of a pronoun used when it's the object of a verb or preposition.
Examples:
* Nominative: *He* went to the store. (He is the subject)
* Objective: The store helped *him*. (Him is the object of the verb "helped")
Remember: It's important to use the correct case for pronouns to ensure clear and grammatically correct writing.