The subject of the predicate "were" in the sentence is "collection," a singular nouns phrase. We need its predicate to be in singular form as well for proper verb-noun agreement. The only answer choice that is in singular form is "was," so "was" is the correct answer. Each of the other answer choices—"were," "are," and "exist"—are in plural form, and are therefore incorrect.

The underlined portion of this sentence is referring to "the number of students," a single subject—"students" is not the subject that needs to match the verb in number; it is the object of the preposition "of." The subject is "number." Try taking out all the extra information between the subject ("number") and the verb phrase ("have more than doubled"), and you will be able to see more clearly that the singular "has" is needed in this case. If you take out this information, the sentence reads, "The number have more than doubled," which is incorrect. There is no need for the "has been doubling" in the sentence as there is no reason to switch to a tense other than the present perfect.

With a collective noun like "jury," if the group or collective is all acting in a unified way it takes the singular "is" instead of the plural "are." Here, the entire "jury" is "being sharply divided," so "is" is the correct verb to use.

The subject of the sentence is singular, "the boy," and not the plural "many friends," meaning the verb needs to be singular as well. Additionally, the sentence must keep the same meaning, that they boy is doing the celebrating. "Celebrates" is the correct answer choice.

The verb "annoy" is used with the subject "styles," although the prepositional phrase "of leadership" and the adverb "frequently" come between the two words. Therefore, the verb form must take a plural form to match the subject. "Styles...frequently annoy" is the correct answer form.

The verb in the sentence, written in the underlined portion as "face," must actually be in the singular form "faces." The subject of the sentence is "every," which is actually a singular form, even though the verb sits next to "new coaches." "The new coaches faces" is the correct answer.

The problem with the sentence is that the verb "are" is a plural form, but is matched with "One," a singular noun, even though "boys" is the closest word to the verb in the sentence. The correct answer is "One of the boys is coming over."

The underlined phrase has an incorrect use of the verb "is," as the subject, "players," is a plural form. The verb needs to be similarly plural. "There are no players" is the correct answer choice.

The subject of the sentence is "youngest girl," a singular noun. Although the verb is next to the plural "students," a plural, the verb form must be a singular verb. Additionally, a superlative need a comparison to be used appropriately, making "has dark hair" the correct answer choice.

The issue with the sentence as it is written is that the subject of the sentence, "every night," is singular, but the verb "were" is plural. The subject and the verb must agree. The correct answer is "Every night for five straight nights was well below freezing."