Grammar Tips: Subject–Verb Agreement

When writing in English, it’s important to make sure that the subject and verb in a sentence agree. This post covers the basics of subject–verb agreement, which will give you the foundations to build more complex sentences.

Subject–Verb Agreement: The Simple Present Tense

In a sentence, the subject is the thing doing the action, while the verb is the action itself. In the simple present tense, singular first- and second-person pronouns (e.g. ‘I’ or ‘you’) and plural pronouns (e.g. ‘we’ or ‘they’) are followed by a base verb (i.e. the most basic form).

When we use singular third-person pronouns (i.e. ‘he’, ‘she’, ‘it’), the third-person singular verb form (which typically ends in ‘s’) is used instead:

Singular third-person verbs are also used when the subject in a sentence is a singular noun:

The computer breaks down all the time.

If the subject is a plural noun, the verb changes back to the base form:

These computers break down all the time.

The girls go to ballet twice a week.

And keep in mind that uncountable nouns take third-person singular verbs:

The milk tastes amazing!

The water flows strongly here; be careful!

Subject–Verb Agreement: The Simple Past Tense

When using the simple past tense, the verb doesn’t change depending on the subject. Regular past tense verbs typically take the suffix ‘-ed’ (e.g. ‘I played football yesterday’). But there are some irregular past tense verbs: e.g. ‘swam’ (not ‘swimmed’).

In fact, some of the most commonly used verbs in English are irregular! The base verb ‘be’, for example, has various forms depending on tense and person:

1^st person singular: I am hungry.

2^nd person singular: You are funny.

3^rd person singular: She is smart.

1^st person plural: We are confused.

2^nd person plural: You are lost.

3^rd person plural: They are terrible.

Subject–Verb Agreement: Parenthetical Statements

Picking the correct verb form can be tricky when a parenthetical phrase separates the subject and the verb:

The boy, accompanied by his pet koala bear, enjoys hiking in the woods.

Here, we use the singular ‘enjoys’ because the koala bear is part of a parenthetical phrase, as indicated by the commas. In other words, the koala bear could be removed from the sentence without changing its basic meaning.

If the boy and the koala bear were equally important, we’d use a compound subject:

The boy and his pet koala bear enjoy hiking in the woods.

Here, since compound subjects are treated as plural, a plural verb is used.