Printable version of Subject-verb agreement (PDF).
Subject-verb agreement involves using the right verb form for the noun that holds the subject position in your sentence. If the grammatical subject of your sentence is singular, you use a singular verb form; if it is plural, you use the plural verb form. Subjects and verbs are said to disagree when verb endings do not correspond to the subject.
Personal endings for regular English verbs:
You (plural) walk
Note that the only time you need a different ending is with the third person singular form. You also need to consider different forms with some common irregular verbs:
You (plural) are
You (plural) have
These common irregular verbs are especially important because they are also auxiliary verbs:
She is walking to school.
She has walked to school.
They are walking to school.
They have walked to school.
Common Errors in Subject-Verb Agreement
Errors in subject-verb agreement occur much more frequently when sentences become more complicated. Be careful of the following tricky situations:
When there are several words between the subject and verb. The tendency is to make the verb agree with the closest noun, which is not correct.
e.g., The reliability of many standard intelligent tests have been challenged in recent years.
The subject of this sentence is reliability so the verb should be has been challenged.