Final answer:
The indefinite pronouns 'everybody', 'no one', 'anybody', and 'someone' all require a singular verb when they are the subject of a sentence. This application of singular verbs maintains subject-verb agreement by standard English grammar rules, and it is also recommended to use gender-neutral language such as 'their' to refer to these indefinite pronouns.
Step-by-step explanation:
In English grammar, indefinite pronouns refer to people or things in a general way, without specifying exactly who or what they are. Many indefinite pronouns take a singular form. Specifically, the indefinite pronouns everybody, no one, anybody, and someone all require singular verbs when they serve as the subject of a sentence. For example, in sentences like 'Everyone on the team practices all season' and 'No one among the accused suspects admits to the crime', 'everyone' and 'no one' are the subjects and the verbs 'practices' and 'admits' are singular to match the indefinite pronoun subjects. This is in line with standard English agreement rules between subjects and verbs.
In contrast, certain other indefinite pronouns such as both, few, many, others, and several take plural verbs. For example, 'Several of the athletes on the team come from the same high school' demonstrates the use of a plural verb with the plural indefinite pronoun 'several'.
Moreover, it is important to consider the preferred pronoun reference to avoid gender-biased language. Instead of using 'his' or 'his or her' with indefinite pronouns, one can use 'their' to maintain gender neutrality, as in 'Everyone has their own opinion.'