When writing sentences, the verb conjugates according to the subject. The general rule of thumb for conjugating verbs is that if there's one person, place, or thing as the subject (not just one noun), then the verb is conjugated in the singular. If there are multiple people, places, or things, then the verb is conjugated in the plural. In other words, the verb and subject agree in number.
When you have a compound subject (when you have a number of singular or plural nouns that are all the subject of the sentence), you need a plural verb. These compound subjects use the word “and” to link the list of nouns:
Mass nouns, or uncountable nouns, use a plural form and take a singular verb. You’re most likely familiar with some of these from academia:
Like mass nouns, collective nouns are made up of several parts but use a singular verb:
Note that collective nouns use a singular verb in American English, but a plural verb in British English.
Take note! One salient exception to this rule is the word data. Depending on your discipline, data will be used as a singular or a plural noun. A Latin word, data is plural (the singular is datum). In psychology and other scientific disciplines that use data on a daily basis, for example, data takes a plural verb:
The data are inconclusive. (psychology)
But when used colloquially (such as in a news cast or in non-scientific settings), data may be used in the singular:
The data supports the politician's claim.
Learn how data is used in your discipline, and pick the correct verb conjugation accordingly. Because language is fluid and always developing, you may find that use of data as a singular will only continue to grow, just like the plural noun media (singular: medium. Media is also a word borrowed from Latin.)
Pronouns That Use Singular Verbs
Certain words can function as a subject in the sentence when used as a pronoun. These use singular verbs:
Agreement can be tricky if you are writing long, complex sentences where the subject and verb are not side-by-side. To make editing easier, try reading sentences aloud. Often you’ll hear if something is off. You can also check for subject-verb agreement by asking which subject is doing the verb to find the subject, and then putting the subject and verb side-by-side. Remember to check if the subject is being used as a singular or a plural, or if multiple nouns are being linked together to form a subject. If you’re ever unsure about whether the subject needs a singular or a plural verb, look the word up in the dictionary. The definition will also include how to use the word in a sentence.