The majority of English words rely on their position within a sentence rather than their form to show their function. In most instances, the placement of a word determines whether it is a subject or object. Certain nouns and pronouns, however, change their form to indicate their use.
Case is the form a noun or pronoun assumes that shows how it is used in a sentence.
English has three cases:
• Nominative case
• Objective case
• Possessive case.
In general, pronouns take the nominative case when they function as the subject of a sentence or clause and the objective case when they function as the object of a verb or preposition. Pronouns and nouns take the possessive case to indicate ownership.
Nouns change form only in the possessive case.
For example, a dog's bark, Maria's hair.
Some pronouns, in contrast, change form in the nominative, objective, and possessive cases. The following shows how personal pronouns change form in the three different cases.
Subject (Nominative case): I, you, he, she, it, we, they, who, whoever
Object (Objective case): me, you, him, her, it, us, them, whom, whomever
Possessive (Possessive case): my, mine, your, his, her, hers, its, our, ours, their, theirs, whose, whosever
The nominative case is sometimes called the "subjective" case because it is used when pronouns function as subjects.The following examples illustrate how personal pronouns are used in the nominative case.
EXAMPLES OF PERSONAL PRONOUNS IN THE NOMINATIVE CASE:
Subject of a Verb:
We understand that they will be late.
Neither she nor I will be attending.
Who is responsible for this situation?
Subject of a Clause:
Give a tip to the waitress who helped us.
Whoever wants extra hours must see me today.
She is the person who recommended the plan.
Appositive identifying a subject (An appositive is a word or a phrase appearing next to a noun or pronoun that explains or identifies it and is equivalent to it):
Both physicists, Marie Curie and he, worked on isolating radium.
Both community members, she and her brother, traveled to Albany this weekend to lobby for increased state aid.
It is I.
The primary supervisor is she.
The fastest runners are Lenore and he.
We Malones are fond of traveling.
The predicate nominative is the noun or pronoun after a linking verb that renames the subject. As a general rule, the linking verb to be functions as an equals sign: the words on either side must be in the same form. Since the predicate nominative can sound overly formal in speech, many people use the colloquial: It's me. It's her. It must be them. In formal speech and edited writing, however, the nominative forms are used: It must be they. The figure at the door had been she, not her husband. In some instances, revising the sentence can produce a less artificial sound.
The delegates who represented the community at last evening's town board meeting were you and I.
You and I represented the community at last evening's town board meeting.
The objective case is used when a personal pronoun is a direct object, indirect object, or object of a preposition.
Bob's jokes embarrassed me.
When you reach the station, call either him or me.
The glaring sun gave my friends and us a headache.
My aunt sent me a scarf from Venice.
Please give him some money.
Object of a Preposition:
From whom did you receive this card?
They fully understood why they had come with us rather than with him.
Let's keep this understanding between you and me.
With than or as
If the word following than or as begins a clause, the pronoun takes the nominative case. If the word following than or as does not introduce a clause, the pronoun takes the objective case. In some instances, the case depends on the meaning of the sentence. To help decide whether the sentence requires a pronoun in the nominative or objective case, complete the clause.
She has been working at Smithson longer than he (has).
Kevin is more proficient at marketing than I (am).
They are going to be informed as quickly as we (were).
I have stayed with Julia as long as she (has stayed with her).
I have stayed with Julia as long as her[as I have stayed with her].
A pronoun takes the possessive case when it shows ownership.
Use the possessive case before nouns to show ownership.
Joan left her coat in the movie theater.
Theirs is the store on the corner.
Our puppy cut its front paw on a rough brick.
Is that book really his?
Use the possessive case before gerunds in most instances.
A gerund is the -ing form of the verb (examples: swimming, snoring) used as a noun. Possessive pronouns and nouns often precede gerunds, as in The landlord objected to my (not me) having guests late at night. In practice, however, both objective and possessive forms appear before gerunds.
My shoveling the snow no doubt saved the postal carrier a nasty fall.
Do you mind my eating the rest of the cake?
She wholeheartedly supported his exercising.
My colleagues were really annoyed by my coughing.
A possessive is not used before a gerund when it would create a clumsy sentence. In these instances, rewrite the sentence to eliminate the awkward construction.
The neighbors on the corner spread the news about somebody's wanting to organize a block party.
We heard the news that somebody wants to organize a block party.
In a Noun Position
Some possessive pronouns—mine, his, hers, your, ours, theirs—can be used alone in a noun position to indicate possession.
This idea was mine, not yours.
Is this article really hers?
Do you believe that it's theirs?
Never use an apostrophe with a possessive personal pronoun. The following personal pronouns are already possessive, so have no need for an apostrophe: my, mine, your, yours, her, hers, its, our, ours, their, and theirs. In addition, do not confuse the contraction it's with the possessive pronoun its.
As mentioned above.