The subject and verb in a sentence must agree in number: Singular nouns and pronouns take singular verbs; plural nouns and pronouns take plural verbs.
Sounds easy, doesn't it? But people make mistakes in subject-verb agreement all the time. This usually happens when
a) the subject is a compound noun or more than one noun joined by and; or
b) when a phrase or clause separates the noun and the verb. People sometimes incorrectly make the verb agree with the nearest noun in the clause rather than with the subject of the sentence.
Wrong: Venus and Mars is a planet.
Right: Venus and Mars are planets.
Wrong: The boys and their mother walks to school.
Right: The boys and their mother walk to school.
Wrong: A Subaru, unlike most station wagons, have all-wheel drive.
Right: A Subaru, unlike most station wagons, has all-wheel drive.
When you're not sure whether you've got it right, isolate the subject and the verb from the other words in the sentence. Do they agree in number?
Don't let the following trip you up, however.
1. Some indefinite pronouns can be singular or plural, depending on the sentence:
All the rent has been paid.
All the tenants have paid their rent.
If none means no one, use a singular verb.
None of the children misses a meal.
2. Some nouns can be singular or plural, depending on how the writer uses them:
Politics is the art of compromise.
Susan's politics are not the issue.
A few nouns that look plural take a singular verb:
The news was all bad.
Economics is the dismal science.
Headquarters wants this report immediately.
