Agreement

 What is "agreement"? 

Agreement is a matching relationship between subject and verb in finite clauses.

The main rule of agreement is simple:
Singular subjects go with singular verb phrases.
Plural subjects go with plural verb phrases.

This rule applies to 3rd person subjects. But there're some exceptions.

1. The rule of agreement

In the Present Tense (3rd person):

• if the noun is singular, the verb must have an -s.
• if the noun is plural, the verb does not have an -s.

	noun	verb
singular	-	+ -s
plural	+ -s	-

Example:
The table needs cleaning.
The tables need cleaning.

1.1. Singular subject + singular verb phrase

singular subject	singular verb phrase	object/complement/adverbial
This dog	looks	smart.
She	does	the cooking.
One apple	has been eaten*	by my friend.

1.2. Plural subject + plural verb phrase

plural subject	plural verb phrase	object/complement/adverbial
These dogs	look	smart.
They	do	the cooking.
Three apples	have been eaten.*	-

* In passive voice, there's no object or complement.

Notes:

A. The noun which marks plural in the subject is the headword of the phrase. It isn't always the noun next to the verb. In the examples below, laws and chair are the headwords. For examples:
1. The laws of science have no exceptions.
2. That chair with the wooden arms belongs to me.

B. Some nouns ending in -s are not plural. For examples: news, measles, mathematics, billiards. For example:
1. Measles is a disease.
2. Billiards is a game.
Also, some plural nouns do not end in -s, for examples, men, women, children, etc.

C. The singular verb is the form we use when the subject is : (a) uncountable or (b) a clause.
(a) uncountable: Milk keeps children healthy.
(b) a clause: [What she wants] is your time. (The subject here is in [ ].)

1.3. Agreement for tenses

Verbs have singular and plural forms only in present tense. For examples: looks ~ look, goes ~ go, comes ~ come, etc. In the past tense there is no agreement problem because the verb doesn't change. Let's see examples below:
1. The apple looked delicious.
2. The apples looked delicious.

But the verb be has singular and plural forms in both the present tense and the past tense. It must follow the rule of agreement in the past tense too.

tense	singular	plural
present	The box is empty.	The boxes are empty.
past	The box was empty.	The boxes were empty.

Modal auxiliaries like can, will, and would do not have singular and plural forms. They're the same for all subjects. Let's see examples below:
1. I can sing.
2. She can sing.
3. They can sing.

2. Special problems of agreement

There're some exceptions to the rule of agreement, and sometimes we can choose whether to follow the rule of agreement or not.

2.1. Agreement with and and or

Where the subject consists of two or more items joined by AND, the subject itself is plural, and is followed by a plural verb. For example: My wife and I both have a job.

But two singular noun phrases joined by (either) ... or are followed by a singular verb phrase. Let's see example below:
1. I think mathematics and science are her favourtie subjects.
2. I don't know whether mathematics or science is her favourite subject.

Note: The usual rule for or is that the verb phrase matches the last of the items joined by or. Example:
1. Either the teacher or the students were wrong.
2. Either the students or the teacher was wrong.

2.2. Agreement with quantity words

As subjects, the pronouns any, either, neither, and none sometimes take a singular verb, and sometimes take a plural verb. For example:
(A):
1. I don't think any of the winners deserve/deserves a prize.
2. I don't think either of the winners deserve/deserves a prize.

(B):
1. Their sons are grown up, but none (of them) is/are married.
2. Their sons are grounw up, but neither (of them) is/are married.

The singular verb is preferred in formal "correct" English. But often, we prefer the plural verb when a strong idea of "plural" is present, for example, when none is followed by a phrase like of them, containing a plural noun or pronoun. For example: None of our children are married.

2.3. Agreement with nouns such as number, majority, and plenty

Usually, we use nouns such as number, majority, and plenty with a plural verb, in spite of the rule of agreement. For example:
1. A (large) number of the students (was) were happy with their exam results.
2. The majority of the students (was) were happy with their exam results.
3. Plenty of the students (was) were happy with their exam results.

2.4. Agreement with group nouns

When singular group nouns such as audience, committee, family, government, team act as subject, the verb sometimes is plural, especially in Great Britain. For example:
1. Our family has breakfast at 8:00 o'clock.
2. Our family have breakfast at 8:00 o'clock.

It's best to choose the singular verb, except where the idea of "plural" is strongly suggested. For example:
The audience were clapping and waving their arms when the two team arrived.

Here was would be odd because of the "plural idea" expressed by their arms.

Be careful to avoid errors in agreement, as these are common:
1. Sam want his wife back. (wants is correct).
2. The use of social media have become very popular. (has is correct)

I hope this article helps. If you have any question, please leave a comment below.