Subjects and verbs (or predicates) must agree in number. A singular subject takes a singular verb; a plural subject takes a plural verb.
The subject does not necessarily have to precede the verb. It may be found anywhere in a sentence:
Along the row of houses was planted a lone palm tree.
(Tree is the subject, singular, and agrees with the singular verb was planted.)
The word there is never a subject. It may be an adverb or an expletive. (As an expletive it does not function except to point out or indicate presence.)
There go six of the students now.
(Six is the subject, plural, and agrees with the plural verb go; there is an adverb.)
There is only one person here now.
(Person is the subject, singular, and agrees with the singular verb is; there is an expletive.)
The following indefinite pronouns used as subjects are singular and take singular verbs: any, anyone, anybody, anything, someone, somebody, something, everyone, everybody, one, no one, nobody, nothing, each, either, neither. (These signify each individual separately.)
Nothing is that important.
(No one thing is that important.)
The following indefinite pronouns are plural: few, several, some, both. (These signify more than one individual collectively.)
Both are welcome.
Collective nouns are singular in form but may be singular or plural in meaning; so when used as subjects, they take their verb form from their meaning.
The committee is seated. (as a unit)
The committee have disagreed among themselves. (Obviously, members are considered individually here; so the verb is plural, indicatingseparate individual action rather than collective action as one unit.)
Ordinarily a collective noun in its singular form takes a singular verb.
The object of a preposition is not a subject. The noun or pronoun following a preposition is NEVER a subject.
The flock of geese flies South each year. (flock, subject, singular--not geese.)
The flocks of geese fly over our house. (flocks, subject, plural--not geese.)
The head of the organization is the man to see. (head, singular, subject--not organization.)
Modifying phrases are not subjects.
The textbook, as well as the reference books, is difficult to read. (The phrase as well as the reference books is not part of the subject; subject book, singular agrees with is, singular.)
When either or neither is used as a subject, the verb is singular.
Either of the books is acceptable.
Neither of the boys is allowed to go.
When either/or or neither/nor is used as a connective, the verb takes its form from the subject closer to it.
Neither Tom nor the boys are to blame. (are, plural, agrees with boys)
Either the boys or Tom is to blame. (is, singular, agrees with Tom)
Doesn’t is the contraction for does not and is singular, while don’t is the contract for do not and is plural. There’s is the contraction for there is.
They don’t want us here.
It doesn’t annoy me.
There’s no one here. (There is no one here.)
Compound subjects (two or more subjects) take plural verbs.
If the same person is indicated by two different titles, the verb is singular.
The boy and his parents were leaving. (Compound subject)
The secretary and treasurer was giving her report. (One person holding two offices)
The secretary and the treasurer were going over the accounts. (two people)
Words that represent units are used singularly and take singular verbs.
Mathematics is difficult for me. (There is no form of mathematic.)
Ten miles is a long walk. (Ten miles is considered as a unit.)