In a world where using singular “they” is becoming more commonplace, subject-complement agreement can sometimes get quite confusing. It is important to remember that although the singular “they” is quite popular in the spoken word, there are still writing styles that don’t recognize it as grammatically correct. This is why it is still important to be sure that your complement, or that part of the sentence that completes the sentence’s meaning, matches your subject. This means proofreading your work carefully for subject-complement agreement errors.

What Is Subject-Complement Agreement?

The subject-complement agreement definition is not as hard as it sounds. First, let’s break it down into two parts: a subject and a complement.

A subject is the part of the sentence that is being or doing something. If you can find the verb, you can find the subject. For instance, in the sentence “I ran to school,” the subject is “I” because it performed the action, “ran”.

A complement is the noun that completes the meaning. For instance, in the sentence “He is my brother,” the words “my brother” complement the subject “He.” (But don’t confuse “complement” with “compliment”—”complement” refers to something that completes, while “compliment” is a polite expression of praise or admiration.)

The trick to understanding subject-complement agreement is that occasionally you run into issues where the subject and complement do not agree.

How To Use Subject-Complement Agreement

Follow these steps to ensure that your subject-complement agreement is grammatically correct:

1. Identify Subject-Complement Errors

One of the first steps in ensuring subject-complement agreement is to identify obvious errors. Basic grammar rules tell us that if the subject is singular, the complement should also be singular. If the subject is plural, the complement should be plural.

– INCORRECT: The dog wagged their tail.

– CORRECT SINGULAR: The dog wagged its tail.

– CORRECT PLURAL: The dogs wagged their tails.

In certain writing styles, such as AP style, even if the gender of the subject is not identified, a singular pronoun is still required.

– INCORRECT: The child showed their painting to their parents.

– CORRECT SINGULAR: The child showed his painting to his parents.

– CORRECT SINGULAR: The child showed her painting to her parents.

– CORRECT PLURAL: The children showed their paintings to their parents.

When writing about businesses, subject-complement agreement can get tricky. If you refer to the subject as singular, then the complement should be singular. Use the plural complement if you are talking about businesses or other subjects in the plural.

– INCORRECT: Although the company provides construction services, they don’t offer painting.

– CORRECT SINGULAR: Although the company provides construction services, it doesn’t offer painting.

– CORRECT PLURAL: Although the companies provide construction services, they don’t offer painting.

2. Use Subject-Complement Agreement With Collective Nouns

Collective nouns are nouns that encompass a group of people but look singular. This is the case of words such as family, group, assembly and so forth. If the collective noun is shared by a plural subject, you still use the singular complement.

– CORRECT SINGULAR: She told her crew to wait.

– CORRECT PLURAL: They told their crew to wait.

3. Understand Countable vs. Abstract Complements With Plural Subjects

Countable Complements

Countable complements are just that – they can be counted. This may be things like body parts and objects. When used with a plural subject, countable complements should typically appear as plural.

– CORRECT PLURAL: When she asked if they understood, they shook their heads.

Abstract Complements

Abstract complements are those that are not easily counted. These could be ideas or subjects that encompass more than one thing, similar to a collective noun

– INCORRECT: The teachers taught sciences at the high school.

– CORRECT PLURAL: The teachers taught science at the high school.

Sometimes it is difficult to tell which form is absolutely correct. Some scholars say it may ultimately come down to what sounds right to the writer or reader.

– The students drove their cars to school.

– The students drove their car to school.

Depending on who is reading these sentences, either one might be considered correct. If I had to pick one as correct, I would choose “drove their cars,” which makes more sense to me as I imagine each student has his or her own car. But, wait. Does each student have multiple cars? Or did a group of students drive in a single car? See the confusion? To avoid ambiguity, you may need to add more information or rewrite the sentence so the meaning is clear.

– Each student got into his or her own car and drove to school.

– The students all got into their friend’s car, and then their friend drove them to school.

What Is the Correct Form of Subject-Complement Agreement?

The most important thing to remember about subject-complement agreement is to keep singular with singular and plural with plural. For the most part, errors with subject-complement agreement are pretty harmless unless you are a grammar snob.

What is the most confusing subject-complement agreement you have ever come across? How did you fix it? Share your thoughts and tips in the comments below!