Sentence Structure Errors
Pronoun-antecedent Disagreement
Pronoun-antecedent disagreement
An antecedent is a word to which a pronoun refers.
A pronoun must agree with its antecedent in number and gender.
- If the antecedent is plural, the pronoun must be plural
- If the antecedent is singular, the pronoun must be singular.
- If the antecedent is masculine, the pronoun must be masculine.
- If the antecedent is feminine, the pronoun must be feminine.

John gave
his old textbooks to a friend.
The pronoun is his and it refers to the noun
John. Therefore, John is the antecedent of the
pronoun his. Because John is masculine,
the pronoun is his. Because John is singular, the pronoun
must be singular.

The boys donated
their books to a charity.
The pronoun is their and the antecedent is
boys. Because boys is plural, the pronoun must
be plural.

Offer to run on behalf of an injured runner, and then give
them
a detailed account of the race.
To determine if the pronoun agrees with the antecedent, first find the pronoun.
In this sentence it is them. Then ask "To whom does the
word them refer?" The answer is runner.
However, runner is singular but them
is plural. Therefore, the sentence has pronoun-antecedent disagreement, rather
than pronoun-antecedent agreement.
To correct this sentence, you must make the pronoun agree with its antecedent.

Offer to run on behalf of an injured runner, and then give
him a detailed account
of the race.
The pronoun now agrees with its antecedent in number; both are singular. However,
does it agree with its antecedent in gender (male or female)? Since we don't know
whether the runner is male or female, we can use either him
or her, or just one of them.

Offer to run on behalf of an injured runner, and then give
him or her a detailed
account of the race.

Offer to run on behalf of an injured runner, and then give
her a detailed
account of the race.
Indefinite pronoun
The biggest problem for most students in subject-verb agreement is the use of an indefinite
pronoun in the sentence.
Indefinite pronouns are words like anybody,
anyone, anything, each, everybody,
everyone, everything, nobody, somebody, and
someone,
which do not refer to a definite person or thing. Because
these indefinite pronouns are singular, the personal pronouns which refer to these
words must be singular as well.

When someone loses a job,
they want a bit of hope.
The indefinite pronoun someone is singular and the personal pronoun they is plural. Therefore, there is pronoun-antecedent disagreement.
The sentence can be corrected in the following ways:

When someone loses a job,
he wants a bit of hope.

When someone loses a job,
she wants a bit of hope.

When someone loses a job,
he or she wants a bit of hope.
Sentence # 1: There are many questions a person needs
to consider when they are ready to retire.
The pronoun in this sentence is they, but the antecedent is person.
However, person is singular while they is plural. The pronoun does
not agree with its antecedent in number.
Correction for sentence # 1:
Change the pronoun to agree with the antecedent.

There are many questions a person needs to consider when
he
is ready to retire.
Note: Instead of using he in the above sentence, you could have used
she or he or she.
Sentence # 2: Everyone has to make their own decision
about which model of car to purchase.
The pronoun in this sentence is their, but the antecedent is everyone.
However, everyone is singular while their is plural. The pronoun does
not agree with its antecedent in number.
Correction for sentence # 2:
Change the pronoun to agree with the antecedent.

Everyone has to make
his own decision about which model
of car to purchase.
Note: Instead of using his in the above sentence, you could have used
her or his or her.