Subject-verb agreement is the rule that a verb matches its subject in number. A singular subject takes a singular verb, a plural subject a plural verb:
- The dog barks. One dog, singular verb.
- The dogs bark. More than one, plural verb.
In English the difference usually shows only in the present tense, in the -s on the third person singular (she writes, they write), and in the forms of to be (is and are, was and were) and to have (has and have). Native speakers get the simple cases right without thinking. Mistakes creep in when the subject is hard to find.
The cases that cause mistakes
Words between the subject and the verb
The verb agrees with the subject, not with the noun closest to it. In The list of names is on the desk, the subject is list, so the verb is singular, even though names sits right next to it. Phrases such as as well as, along with and together with do not change the subject either: The manager, along with her team, is travelling.
Either/or and neither/nor
When two subjects are joined by or or nor, the verb agrees with the nearer one: Neither the manager nor the staff were told, but Neither the staff nor the manager was told. If that sounds awkward, put the plural subject second.
Subjects joined by and
Two subjects joined by and are plural: The cat and the dog are asleep. The exception is a pair that names one thing: Fish and chips is my favourite meal.
Collective nouns
Words such as team, family, government and committee name a group. American English almost always treats them as singular: The team is winning. British English allows the plural when the members are thought of as individuals: The team are arguing among themselves. Either way, keep the verb and the pronouns after it in step: The team is ready for its match, or The team are ready for their match. See American and British Spelling for more differences between the two.
Indefinite pronouns
Everyone, everybody, someone, nobody, each and either are singular: Everyone has a ticket. None can take either form; none of the cake is left but none of the guests have arrived is as acceptable as has.
There is and there are
In a sentence that starts with there, the subject comes after the verb, which makes it easy to miss: There are three reasons, not There's three reasons. The contraction there's is especially tempting in speech; in writing, check what follows it.
Amounts and titles
An amount thought of as one sum is singular: Ten euros is enough. Three weeks is a long time. So is the title of a single work: The Hours is a novel by Michael Cunningham.
How to check a sentence
Find the verb, then ask "who or what is doing this?". Strip out everything between the answer and the verb, and read the two together: the list ... is, everyone ... has. If the pair sounds right on its own, it is right in the full sentence.
How the spell checker helps
Agreement errors are grammar mistakes, so a spelling check alone does not see them: results and shows are both correctly spelled. The Spell Checker checks grammar too, and its rules flag many agreement slips such as he go or the results shows, with the matching verb form as the suggestion. The further apart the subject and the verb are, the harder any automatic check finds it, so long sentences deserve the reading test above.