The subject and the verb must always agree in number. Therefore, a singular subject requires a singular verb form: The dog runs out of the house.

A plural subject requires a plural verb form: The dogs run out of the house.

Singular and plural verb forms should be second nature to you - you use them so often that there is nothing to memorize. You would never write the dog run out or the dogs runs out.

However, you may get confused when the subject is cleverly hidden in the sentence. In such a scenario, you may be unsure whether the subject is singular or plural! If you do not know the number of the subject, then you will not be able to select the verb form that agrees with the noun.

Consider this example: The discovery of new medicines were vital to the company’s growth.

If you ask yourself “What is vital to the company’s growth?” you may answer the “Discovery of new medicines is”. Therefore “The discovery... was” is correct.

The key to making subjects and verbs agree is to find the subject that goes with a particular verb. To find the subject, you must ignore all the words that are not the subject. You do that by eliminating all the non-essential information between the subject and the verb.

Generally, the subject is hidden in a few ways. The most common way to eliminate these Middlemen or Warm-ups by inserting words between the subject and the verb or putting a significant number of words in front of the subject.

This strategy will enable you to easily identify the subject and determine whether there is an error in subject-verb agreement.

WRONG: Changes for the new and improved SAT Writing section is going to be implemented soon.

Correct: Changes for the new and improved SAT Writing section are going to be implemented soon.

WRONG: When the auditors left, the executive who had been interviewed were glad.

Correct: When the auditors left, the executive who had been interviewed was glad.

Now, let’s walk through a tricky example: Mastery of magic tricks that truly (surprise/surprises) the audience (require/requires) lots of time.

Here, we have to identify the subject of two verbs.

First, cross out the warm-ups and the middlemen: Mastery of magic tricks that truly (surprise/surprises) the audience (require/requires) lots of time.

Now it’s easy to see that mastery is the main subject of the sentence. Mastery is singular, so we need the singular verb requires.

Now, let’s get back to the first verb, which is included in part of the sentence that has been crossed out. We need to ask ourselves the question “What is truly surprising the audience?” Magic tricks! Magic tricks are plural, so we need the plural verb surprise.

The correct sentence: Mastery of magic tricks that truly surprise the audience requires lots of time.

Subject Comes After the Verb

In rare instances, the subject follows the verb. In these cases, it can be particularly challenging to identify the subject and determine if there’s an error in subject-verb agreement.

Example: In the trunk of my car resides 15 empty water bottles.

In the sentence, what’s residing? The water bottles. Because the subject is “water bottles,” the verb should be in the plural form.

This is the correct version of the sentence: In the trunk of my car reside 15 empty water bottles.

The correctly written sentence may sound more awkward to you because the singular noun “car” is placed right next to the plural form of a verb. You should focus on the rules and strategies as opposed to just relying on what “sounds right.”

Collective Nouns

A common error in the agreement of subjects and verbs comes in the use of collective nouns. Collective nouns refer to groups of things or people but act, grammatically, as singular objects. If the subject of a sentence is a collective noun, the verb of that sentence should remain in its singular form.

Wrong: The firm are still making a decision on your employment status at the moment.

While “the firm” is composed of many more than two people, here the collective stands for singular grammatical entity.

Correct: The firm is still making a decision on your employment status at the moment.

Compound Subjects

As discussed in an earlier chapter, the coordinating conjunction “or,” when used to connect two nouns in a sentence, renders the subjects it connects singular. When “and” is used in this fashion, the two subjects connected are joined, and must be treated as plural.

Wrong: The umbrella or the hat are at the bottom of the stairs.

This sentence is incorrect because while “or” connects the two subjects, it also treats them both as singular entities.

Correct: The umbrella or the hat is at the bottom of the stairs.

Watch out for singular nouns ending in “s.” Just because a noun ends in “s” does not necessarily mean it is plural.

example: Mathematics is a subject that I just cannot get my head around.

This sentence is correct! The speaker is referring to one subject. He or she is not referring to many “mathematics,” just one.

A more complicated example in which a prepositional phrase is placed at the beginning of the sentence is:

Wrong: In between the cushions of my couch is change and an old pen.

What’s in between the cushions? Change and an old pen. The sentence has two subjects (change and an old pen)therefore, the verb should be plural.

Correct: In between the cushions of my couch are change and an old pen.

Hopefully, you got most of those, if not all, right. Now, try to solve the following examples.

Example 1
Has the girls on the ski team ever competed internationally?
A. NO CHANGE
B. Does
C. Hasn’t
D. Have

Solution: he subject of this sentence is girls. The subject is plural and should have the plural verb - have. The correct answer is D.

Example 2
Borderlands Food Bank, an organization in Nogales, Arizona, rescue millions of pounds of slightly imperfect imported food every year.
A. NO CHANGE
B. have rescued
C. are rescuing
D. rescues

Solution: The subject of the sentence is Borderlands Food Bank - one organization. Therefore, the subject is singular. The only answer option with a singular verb is D - rescues. The correct answer is D.  

Example 3
The time and place for such a large event is subject to approving from the mayor’s office.
A. NO CHANGE
B. For such a large event, the time and place are subject to the approval from the mayor’s office.
C. The time and place for such a large event are subject to the approval by the office of the mayor
D. The time and place for such a large event are subject to be approved by the office of the mayor.

Solution: The subject is both the time and the place.  Therefore, the verb should be in the plural form.  Also, there is an additional error in the sentence in that “to approving” should be “to the approval”. The correct answer is C.

Noun-Noun Agreement

Like subjects and verbs, related nouns in a sentence should also agree in number. When we say, “agree in number,” we mean that plural nouns most often suggest that a corresponding, logically related noun should be plural as well. The same goes for singular nouns. This is probably best illustrated with an example.

Wrong: During our panel, we came up with an answer to all the questions that were asked.

Here, it does not really make sense that “we” had a single answer to “all the questions.” These related nouns should agree in number.

Correct: During our panel, we came up with answers to all the questions that were asked.

The exception to this rule of noun-noun agreement can be found with abstract nouns, which should usually remain singular, even if they are represented by multiple objects.

Wrong: His love for his wife were shown by the many books of poems he dedicated to her.

This sentence, as you can see, reads quite oddly. While “love” and “many books of poems” are, logically related in this sentence (the “books” show the “love”), because “love” is being used here as an abstract noun to represent a singular emotional state, it must remain grammatically singular.

Correct: His love for his wife was shown by the many books of poems he dedicated to her.

Example 4
The frazzled librarian scampered back to the desk. “We checked the cover of all of the books in that sections of the library, but couldn’t find the title Amy requested,” she reported. “We need to log it in the ‘Missing Titles’ list.”
A. NO CHANGE
B. cover of all of the books in that section
C. covers of all of the books in that section
D. covers of all of the books in that sections

Solution: “Books” is a plural noun, and multiple tangible books presumably have multiple covers, so “cover” needs to be changed to “covers.” Only C and D do that. However, D also changes “section” to “sections,” creating an ungrammatical phrase “that sections.” The correct answer choice is C.

Examples 5 - 8
Succulents have become popular houseplants as of late. [5] A few details suggests why this is the case. [6] The plants are adapted to arid climates, so it requires very little water, sometimes needing attention as rarely as once a month. [7] Furthermore, a succulent encompasses a wide variety of unusual forms. Compared to traditional houseplants, succulents look fascinatingly alien. [8] It’s easy to see why they’ve become so popular!

5.
A. NO CHANGE
B. suggest why these are the cases.
C. suggests why this is the cases.
D. suggest why this is the case.

6.
‍A. The plants are adapted to arid climates, so it requires
‍B. The plant is adapted to an arid climate, so they require
‍C. The plants are adapted to arid climates, so they require
D. The plant is adapted to arid climates, so it requires

7.
A. NO CHANGE
B. succulents encompass a wide variety of unusual forms.
C. succulents encompasses a wide variety of an unusual forms.
‍D. a succulent encompasses wide varieties of unusual forms.

8.
A. NO CHANGE
B. It’s easy to see why it’s
C. They’re easy to see why they’ve
D. They’re easy to see why it’s

Solutions:
5. The plural subject “a few details” does not agree with the verb “suggests.” Changing “suggests.” to “suggests” corrects this sentence’s error, but two answer choices do this. Answer choice B changes the phrasing to “why these are the cases.” There is no reason to use the plural in this instance. Answer choice D is correct.

6. Answer choice A refers to “The plants” (plural) before using a singular pronoun “it,” which refers to them incorrectly. Answer choice B does the opposite, beginning with the singular “The plant” and using a plural pronoun, “they.” The passage begins by talking about “succulents,” a plural noun. Nothing in the second sentence suggests that a switch to talking about a singular plant is called for. The correct answer C, the one that refers to the plural noun “the plants,” remains consistent with the passage’s initial plural subject.

7. It doesn’t make much sense that a single succulent would “encompass a wide variety of unusual forms,” so the plural is called for in this sentence, allowing us to narrow our answer choices down to B and C. “A wide variety of an unusual form” is ungrammatical, as you inherently need more than one of something to represent “a wide variety” of it. Thus, the correct answer is B.

8. This sentence is correct as written. “It’s easy to see” is a correct use of a common phrase, and nothing in the passage calls for the use of “they’re” instead of “it’s” in this instance. While B is grammatically correct when read out of the context of the passage, the passage itself discusses succulents in the plural, not as “a succulent.” Thus, it makes the most sense to remain consistent with this stylistic choice, which the correct answer, A, does.