A verb must agree in person and number with its subject.
| Incorrect: | My friend, with his parents, are flying in today to visit me and my family. |
When the subject of the sentence does not agree in number with the verb, the sentence lacks subject-verb agreement. To preserve the subject-verb agreement, singular subjects take verbs marked for singular. Plural subjects must have verbs that are marked for plural.
A verb must agree in number and in person with its subject.
Errors typically occur when the writer does not know whether the subject is singular or plural.
In the sentence above, friend is the only subject and the verb are flying should be in singular form (is flying) to agree with it in number. The phrase with his parents is a prepositional phrase and not part of the subject, so it has no effect on the verb form.
| Correct: | My friend, with his parents, is flying in today to visit me and my family. |
Here is another example:
| Correct: | Neither my mother nor my sisters are coming to visit me this summer. |
Prepositional phrases such as with, together with, along with, as well as are not part of the subject and, therefore, have no effect on the form of the verb. The verb needs to agree in number only with the subject of the sentence.
| Incorrect: | Laura, together with a friend, practice yoga every day. |
| Correct: | Laura, together with a friend, practices yoga every day. |
Compound subjects are joined by and need a plural verb.
Compound subjects joined by and need a plural verb.
| Correct: | Healthy diet and regular exercise are a necessity for a longer, happier life. |
When the compound subject is joined by or, nor, neither. nor, either. or and one part of the compound subject is singular and the other part is plural, the verb needs to agree with the part closest to it.
| Incorrect: | Neither students nor their teacher are participating in this play. |
| Correct: | Neither students nor their teacher is participating in this play. |
If the subject is following the verb in the sentence, rather than preceding it, it still has to agree with it in number.
| Incorrect: | Here's my test scores. |
| Correct: | Here are my test scores. |
Collective nouns which refer to a group of people or things can take either a singular verb or a plural one.
Collective nouns which refer to a group of people or things can take either a singular verb or a plural one depending on the meaning that is being implied. If the collective noun is taken to represent the group as one whole, then the singular form of the verb is used. For example:
| Correct: | The diversity committee was well represented at the last board meeting. |
If individual members are implied, then the verb takes the plural form:
| Correct: | The committee were voting on the representative to the board of directors' meeting. |
| Correct: | The audience was cheering the performer. |
| Correct: | When the concert ended, the audience were reluctant to leave. |
Some nouns occur only in plural form, but they are singular nouns and take a singular verb: politics, news, ethics, measles.
| Correct: | Ethics is an important component of human study. |
Plural nouns of Latin origin take plural verbs (alumni, media, criteria, phenomena). The word data can take both a singular verb or a plural verb. The use of plural is more formal.
| Correct: | Very little data was provided to substantiate the hypothesis. |
| Correct: | The data for the study were collected from over 300 participants. |
Collective nouns which refer to a group of people or things can take either a singular verb or a plural one.
Subjects that express time or amount also take a singular verb.
| Correct: | Forty thousand is an average starting salary for a Computer Science graduate. |
Titles and names of countries take the singular form of the verb.
| Correct: | The Netherlands is a European country that borders Belgium. |