Subject-verb agreement

From Teflpedia

Subject-verb agreement or subject-verb concord is a type of concord found in English and related languages. Typically, a verb must take a verb form that is in concordance with its subject.

Unlike some other languages, English is very lightly inflected. The verb be must agree according to its conjugation, in both the present tense and past tense. The only other agreement is that a third person singular subject must take a third person verb form inflected with a third person -s but only in the present tense and indicative mood.