Subject-verb agreement is one of the most important grammatical rules in English. It means that the verb in a sentence must match its subject in number and person. For example, we say 'He walks' with a singular subject, but 'They walk' with a plural subject.
Let's look at the basic rules for singular and plural subjects. Singular third-person subjects like 'he', 'she', or 'the cat' take verbs ending in -s or -es, such as 'walks' or 'teaches'. Plural subjects like 'they' or 'the cats' take the base form of the verb without -s. Special cases include 'I' and 'you', which always take the base form regardless of being singular or plural.
The verb 'be' is irregular and has special agreement forms. In present tense, we use 'am' with 'I', 'are' with 'you', 'we', and 'they', and 'is' with 'he', 'she', and 'it'. In past tense, we use 'was' with 'I', 'he', 'she', and 'it', and 'were' with 'you', 'we', and 'they'. These forms must be memorized as they don't follow the regular pattern.
There are several tricky cases that often cause mistakes. When phrases come between the subject and verb, ignore them and focus on the main subject. Indefinite pronouns like 'everyone' are singular. With compound subjects joined by 'and', use plural verbs. With 'or' or 'nor', the verb agrees with the nearest subject. Collective nouns can be tricky depending on context.
To master subject-verb agreement, follow these simple steps: First, identify the main subject in the sentence. Second, determine whether it's singular or plural. Third, choose the correct verb form to match. Remember the key patterns: third-person singular subjects take verbs with -s, while plural subjects and 'I' or 'you' take the base form. With practice, subject-verb agreement will become automatic in your English writing and speaking.