Subject-Verb Agreement

The subject and verb of a sentence must always agree in number: a subject that is singular should go with a singular verb; a subject that is plural should go with a plural verb. Matching the subject and the verb is important because it prevents the reader from confusing which noun is the subject.

Example
The girl is walking in the park.

This is a simple sentence, and it is clear to the reader that the subject of the sentence is “girl.” The singular verb “is” agrees in number with the singular subject “girl.”

However, this is not always obvious for more complex sentences. Take for example the following.

Incorrect
Sample 1, in addition to Samples 2 and 3, were found to be contaminated.
Correct
Sample 1, in addition to Samples 2 and 3, was found to be contaminated.

Here, the subject is “Sample 1,” but if the sentence used the plural verb “were,” it would be easy for the reader to think that the subject is not only sample 1 but also sample 2 and 3.

Subject-verb pair examples

Verb Singular subject + verb Plural subject + verb

Be

The study is novel.

The studies are novel.

Make

He makes a cake.

They make a cake.

Conclude

Goldmund concludes that 67% of the samples had been contaminated.

Goldmund and Millstein conclude that 67% of the samples had been contaminated.

Present

The figure presents the results of the simulation.

The figures present the results of the simulation.

Compound Subjects and Verbs

A sentence can have more than one subject per verb. When two or more subjects share the same verb, the subjects are joined with the conjunction “and” or “or.” Subjects joined by the conjunction “and” are always used with a plural verb.

Incorrect
Composite A and composite C was discarded due to surface irregularities.
Correct
Composite A and composite C were discarded due to surface irregularities.

In contrast, singular subjects joined by the conjunction “(either…)or” are used with a singular verb.

Incorrect
We concluded that either composite A or composite C have issues with surface irregularity.
Correct
We concluded that either composite A or composite C has issues with surface irregularity.

The same applies to singular subjects joined by the conjunction “(neither…)nor.”

Incorrect
Neither sample B nor sample D were found to be contaminated.
Correct
Neither sample B nor sample D was found to be contaminated.

However, if the joined subjects are plural, a plural verb must be used.

Incorrect
Neither the patients in group A nor the patients in group B has histories of illness.
Correct
Neither the patients in group A nor the patients in group B have histories of illness.

Occasionally, a compound subject may contain both singular and plural nouns. In this case, the verb should match the form of the noun closest to it.

Incorrect
Neither the main frame of the vehicle nor its additional components needs to be treated with the solution.
Correct
Neither the main frame of the vehicle nor its additional components need to be treated with the solution.

The singular verb “need” is used here because “components” is a plural noun.

More examples of subjects connected with “and”

Subjects that are joined by “and” are used with plural verbs.

Example
The puppy and the kitten are friends.
Example
The behaviors of lipids and proteins were studied in an isolated environment.

More examples of subjects connected with “(either…)or” or “(neither…)nor”

Singular subjects that are joined by “(either….) or” or “(neither…) nor” are connected with singular verbs.

Example
Either the vacuum chamber or the clean room has been damaged.
Example
Neither the vacuum chamber nor the clean room has been damaged.

Plural subjects that are joined by “(either…) or” or “(neither…) nor” are connected with plural verbs.

Example
Either he or she waters the plants.
Example
It is rainy, so neither the park nor the beach is nice to walk on.

Compound subjects that contain both singular and plural nouns are connected by verbs that match the noun closest to it. When one of the nouns connected by “or” or “nor” is plural, the verb must be plural, and the plural subject should be placed next to the verb.

Example
Either he or his daughters water the plants.
Example
Neither the clean room nor the vacuum chambers have been damaged.

Separated subject and verb

Many sentences have phrases or clauses that separate the subject from the verb. This can make it difficult to identify the subject. Take for example the following two sentences

(a)
Many studies on this subject has neglected the effect of oxygen on the fabrication process.
(b)
Many studies on this subject have neglected the effect of oxygen on the fabrication process.

Which sentence is correct? The answer is b. This is because the subject of the sentence is “studies” not “subject.” Using the correct verb form can help the reader better identify the subject of your sentence.

Incorrect
We found that the derivatives of C demonstrates high heat resistance.
Correct
We found that the derivatives of C demonstrate high heat resistance.

By using the correct plural verb, the second sentence makes it clear that “derivatives” is the subject.

Other connectors: “along with,” “as well as,” “in addition to”

Phrases such as “along with,” “as well as,” and “in addition to” are not conjunctions, but they do act as connectors. As mentioned above, subjects joined with the conjunction “and” are always used with a plural verb. This is not the case for “along with,” “as well as,” and “in addition to.”

Incorrect
Composite C, along with composite A, were discarded due to surface irregularities.
Correct
Composite C, along with composite A, was discarded due to surface irregularities.
Incorrect
Composite C as well as composite A were discarded due to surface irregularities.
Correct
Composite C as well as composite A was discarded due to surface irregularities.
Incorrect
Composite C, in addition to composite A, were discarded due to surface irregularities.
Correct
Composite C, in addition to composite A, was discarded due to surface irregularities.

These connector phrases differ from “and” in that they do not create a compound subject. In the above sentences, the subject is “composite C” — not “composite C, along with composite A,” “composite C as well as composite A,” or “composite C, in addition to composite A.”

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Indefinite Pronouns

Another common confusion is whether indefinite pronouns, such as “anything,” should be used with singular verbs or plural verbs. Some indefinite pronouns are always treated as singular while others are always treated as plural. A few of these pronouns may be treated as either singular or plural, depending on the sentence. Common indefinite pronouns: all, any, anything, anybody, anyone, anywhere, every, everything, everybody, everyone, everywhere, some, something, somebody, someone, somewhere, none, nothing, nobody, nowhere, more, most, another, each, one, both, either, few, many, several

Most indefinite pronouns are treated as singular. “Every,” “another,” “each,” and “one” as well as all indefinite pronouns that end with “thing,” “body,” “one,” or “where” are used with singular verbs.

Example
Every sample was treated with the prepared solution.
Example
Another girl asks for paper.
Example
Each of the samples was treated with the prepared solution.
Example
Only one of the boys wants ice cream.
Example
Something is wrong.

On the other hand, “both,” “few,” “many,” and “several” are treated as plural.

Example
Both of the samples were contaminated with ammonia.
Example
Few are happy with the results.
Example
We found that many of the composites were damaged by exposure to air.
Example
Several children look for extra pencils.

A few indefinite pronouns are treated as either singular or plural depending on the sentence. These are “all,” “some,” “any,” “none,” “more,” “most,” and “either.” See the following sentences using the indefinite pronoun “some.”

Example
Some of the samples were contaminated.
Some of the sample was contaminated.

In the first sentence, “some” refers to the “samples,” which is plural and should be used with a plural verb. In the second sentence, “some” refers to the “sample,” which is singular and should be used with a singular verb.

Subjects Placed After the Verb

There are sentences for which the subject follows the verb rather than vice versa. This is true for sentences that begin with “there” or “here” as well as sentences with an inverted sentence structure.

Example
There are five equations that must be considered.
Example
Here is an equation that must be considered.
Example
Behind the building stands a trash can.

As can be seen from the examples above, the same rules of subject-verb agreement apply to sentences with subjects that follow the verb.

Numbers, Percentages, and Amounts as Subjects

Sometimes the subject of a sentence may be a number or quantity. This is particularly common in academic writing, since numerical values are typically important to scientific research. The verb form that should be used with numerical subjects depends on what the number is referring to.

Example
67% of the samples were found to be contaminated.
Example
80 cm of electric tape was cut.

“67%” is referring to the “samples,” which is plural. Therefore, it should be used with the plural verb “were.” “80 cm,” on the other hand, refers to “electrical tape,” which is singular and thus should be used with the singular verb “was.” The same applies to subjects that are proportions.

Example
Almost three-quarters of the samples were found to be contaminated.
Example
Almost three-quarters of the first sample was found to be contaminated.

If the subject is a unified numerical quantity of something, it should be treated as singular.

Example
70 cm is not a sufficient length.
Example
97.5% is a high accuracy that has not been previously achieved.

Collective Nouns as Subjects

Collective nouns are nouns that refer to a unified group of people, animals, or things. The verb form that should be used with such nouns differs for US and UK English. Collective nouns are typically treated as singular in US English but as plural in UK English.

Example
(US) The flock flies to Russia in early summer.
Example
(UK) The flock fly to Russia in early summer.

A flock is a group of birds. According to US English conventions, “flock” should be used with a singular verb. On the other hand, UK English conventions dictate that “flock” be used with a plural verb. This is because US English places emphasis on the unity of the flock while UK English places emphasis on the many birds that make up the flock.

“Emphasis” is the key word here, as the content of a sentence can determine whether a collective noun is treated as singular or plural.

Example
The flock squawk at each other.
Example
The flock is enormous.

Uncountable Nouns as Subjects

Uncountable nouns are of abstract concept or general terms and thus cannot be counted. Examples of uncountable nouns: research, information, progress, equipment, furniture, luggage, flour, cement. Uncountable nouns are always used with singular verbs.

Example
The research found the previous results to be invalid.
Example
Information is a strategic resource.
Example
The cement was poured over the foundation.

Acronyms and Abbreviations as Subjects

The rule for acronyms and abbreviations is simple: check what term(s) the abbreviation/acronym is short for. First, determine whether the full version is singular, plural, compound, or collective and then apply the relevant rules accordingly.

Example
This new SSD is perfect for my PC.

“SSD” stands for “solid-state drive,” which is singular and should be used with a singular verb.

Example
BCS continue to experience the side effects of the treatments they were exposed to.

“BCS” stands for “breast cancer survivors,” which is plural and should be used with a plural verb.