The underlined section of the sentence has a problem with the verb "have." While the verb is situated next to the plural noun "teenagers," the subject of the sentence is the word "each," which is singular. Therefore, the verb needs to be a singular form, and "Each of the teenagers has" is the correct answer choice.

The issue in the underlined portion of the sentence is that the sentence and verb are not in agreement. While the sentence references "classmates," that is in an interrupting phrase set off by commas, and the subject is the singular "teenager." "The teenager, along with her classmates, objects" is the correct answer choice.

The use of "are" is incorrect in the sentence, as it is a plural form and the subject of the sentence, "thing," is in the singular. The verb tense for "are" needs to be adjusted to the singular form; therefore, the correct answer is "is to listen."

This sentence contains an error in subject-verb agreement. The subject of the sentence ("That actor") is singular, so change the plural verb "have" to "has."  Adding a conjunction ("and" or "but") in this case creates a sentence structure error. To avoid wordiness, stay away from answer choices that add additional "-ing" verbs.

With a complex sentence such as this, it’s important to keep track of your subjects and verbs. Although “meteorologists” is plural, the subject of the sentence is the singular “convention,” and therefore the correct verb forms are “was” and “has failed,” not “were” and “have failed.” Similarly, the singular pronoun “its” is correct and the plural pronoun “their” is incorrect.

There are two instances of subject-verb agreement in this sentence: the singular “admissions process” needs to be paired with the singular verb form “ignores,” and the singular “small cadre of underachievers” needs to be paired with the singular verb form “slides.”

Although there are seven gems, the subject of the sentence is "Each" of the gems, which is a singular noun. Therefore, the correct phrase uses the singular past verb form—"was mined from each of the seven continents on Earth."

The singular use of "is going to" is correct, not the plural use of "are going to." This is because the verb "is" is modifying the "one" team that is going to make it, not the plural "teams." The "of the teams" can be taken out to show that one should use "is", not "are": "Only one . . . is going to make it to regionals."

The subject of this sentence, "A combination," is singular, so the predicate should be singular, too. The original text "delightfully entertaining plot twists characterize the novels of Jane Austen" and the answer choice "delightfully entertaining plot twists have characterized the novels of Jane Austen" contain plural predicates and therefore lead to subject-verb agreement errors. 

The answer choice "the fact that she twists the plot in delightfully entertaining ways characterizes the novels of Jane Austen" leads to faulty parallelism and the use of an ambiguous pronoun, and the answer choice "the fact that she twists the plot in delightfully entertaining ways characterize the novels of Jane Austen" leads to errors in both parallelism and subject-verb agreement.

Only answer choice "delightfully entertaining plot twists characterizes the novels of Jane Austen" correctly preserves the parallel structure and avoids any subject-verb agreement errors.

The use of the past tense verb "were" indicates that the main verb of the sentence, "knows," should also be in the past tense, as they should be in agreement. Thus, the verb "knows" needs to be changed to its past-tense form. "No one knew where the paintings" is the only answer choice that correctly does this.