In short, a pronoun is a word that acts as a substitute for a noun. For example: Instead of saying "Martha went to the vineyard and Martha selected some grapes for making wine;" you would say "Martha went to the vineyard and she selected some grapes for making wine."
The pronoun in the sentence is "she," acting as a substitute for the noun Martha. Using pronouns helps to cut out redundancy in communication.
Pronouns, however, are not all the same. There are different cases of pronouns that work to keep the form consistent in an expression. Subjective pronouns are one of three cases used in the English language. A subjective pronoun substitutes for subjects and subject complements. The subject of an expression identifies who or what the expression refers to. A subject complement, on the other hand, will complete the meaning of a subject through either a description or renaming it.
Since case operates as an important grammatical function in an expression, it is crucial to make sure you use the subjective case correctly. With complex expressions, long prepositional phrases and compound subjects, this can pose a challenge for both writers and speakers. As such, it is important to pay close attention when using the subjective case to ensure correct grammatical form and helping to avoid confusion, or even embarrassment.
There are two forms of the subjective pronoun case, singular and plural. Singular subjective case pronouns are: I, you, he, she and it. Plural form subjective pronouns are we, you and they. In order to understand whether you have used the correct subjective pronoun case in an expression, you can conduct a simple test. For example:
"Jane saw the snake and she ran away." To determine if "she" is the correct subjective case, simply say "she ran." You wouldn't say "her ran."