English: Subject and Verb Agreement

Basic Rule:
A singular subject takes a singular verb, while a plural subject takes a plural verb.

Example:
She dances gracefully. (singular)
They dance together. (plural)

Rule 1:
Two singular subjects connected by "or" or "nor" require a singular verb.

Example:
Mom or dad is arriving at 10 in the morning.

Rule 2:
Two singular subjects connected by "either/or" or "neither/nor" require a singular verb.

Example:
Neither Tina nor Anne is available.
Either Tom or Dan is working today.

Rule 3:
If "I" is one of the two subjects connected by either/or or neither/nor,
put it second and follow it with the singular verb am.

Example:
Neither she nor I am going to the party.

Rule 4:
If a singular subject is connected by "or" or "nor" to a plural subject,place the plural subject last and use a plural verb.

Example:
The cook book or the fiction novels go on that shelf.

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Rule 5:
If a singular and plural subject are connected by "either/or" or "neither/nor", place the plural subject last and use a plural verb.

Example:
Neither Kim nor the others are allowed to enter the room.

Rule 6:
Use a plural verb with two or more subjects if they are connected by "and".

Example:
The scepter and the crown are symbols of a king.

Rule 7:
If the subject is separated from the verb by words such as "along with," "as well as," "not," or "besides," ignore these expressions when determining whether to use a singular or plural verb.

Examples:
Intellect, as well as passion, is the key to his success.
Nina, along with her team, is coming today.

Rule 8:
The pronouns "each, everyone, every one, everybody, anyone, anybody, someone, and somebody" are singular and require singular verbs (regardless of the word the follow).

Examples:
Each of the boys dances well.
Someone from the teens is left-handed.

Rule 9:
With words that indicate portions — percent, fraction, part, majority, some, all, none, remainder, etc — look at the noun in your of phrase (object of the preposition).

If the object of the preposition is singular, use a singular verb.
If the object of the preposition is plural, use a plural verb.

Examples:

Forty percent of the cake was eaten.
Forty percent of the cakes were eaten.

One-half of the city is affected by flood.
One-half of the people are affected by flood.

Rule 10:
The expression "the number" is followed by a singular verb while the expression "a number" is followed by a plural verb.

Examples:
The number of people we need to hire is ten.
A number of people have spoken about this issue.

Rule 11:
If "either" and "neither" are subjects, use singular verbs.

Examples:
Neither of them is guilty.
Either of us is allowed to do the job.

Rule 12:
In sentences beginning with "here" or "there", the subject follows the verb.

Examples:
There are four horses on the farm.
There is a horse on the farm.

Rule 13:
Use a singular verb with "sums of money" or "periods of time".

Examples:
Five thousand pesos is a high price to pay.
Five years is the maximum sentence for that offense.

Rule 14:
Sometimes the pronoun "who", "that", or "which" is the subject of a verb in the middle of the sentence. The pronouns who, that, and which become singular or plural according to the noun directly in front of them.

If that noun is singular, use a singular verb. If it is plural, use a plural verb.

Examples:
Sam is the columnist who writes that famous article.
He is one of the employees who do the job.

Rule 15:
Collective nouns such as "team" and "staff" may be either singular or plural depending on their use in the sentence.

Examples:
The staff is in a meeting.
(Staff is acting as a unit here)

The staff are in disagreement about the findings.
(staff are acting as separate individuals in this example)