The use of the verb "learn" is essentially as a modifier of the students "shock." This means that "learning" must be turned into a form that will describe why the students were "shocked." "Were shocked to learn," using an infinitive form, is the best choice among the answers.

We know that the proper tense to describe an event that happened "over the course of past year" is the present perfect, which narrows down potentially correct answer choices to either "have increased the company's profitability" or "has increased the company's profitability."

Since the subject of the increasing event is "wave," not "advances," we should go with the answer choice that uses the singular verb—"has increased the company's profitability."

The sentence describes what the soldier had already done to his own body. The use of "himself" is correct and necessary to show who the action was done to, but the action occurred in the past, meaning the appropriate verb form is "backed." The correct answer choice is "had backed himself."

The verb in the underlined portion of the sentence is in the present tense, while the verb in the first part of the sentence is in the past tense. The two verbs need to match their tenses due to the construction of the sentence. The correct answer choice is " none proved satisfactory."

The example sentence features a verb tense error. Since "described" is in the past tense and the writing Boswell did about Johnson contains descriptions of Johnson, the verb "writing" should agree with the tense of "described." Replacing the underlined section with "and wrote that" is the correct answer.

While "asserts" and "says" are both potentially correct verbs to insert, those options were in the present tense, and thus would be incorrect in this context.

The phrase "and has written" would need to be a separate clause, and would require a comma preceding it to be correct.

The use of the verb "paint" as the first word in the final phrase is incorrect, as it needs to be a present progressive verb, "painting," to correctly describe the action continuing after the present perfect "have begun." The only answer choice that uses the correct verb form is "painting him as a war criminal and a monstrous villain," making it the correct answer.

This sentence is structured as an independent clause about a priority and then a clarification of what that priority is.

The only appropriate punctuation here is a colon, which will provide that correct structural division and allow the second part of the sentence ("studying physics before her final exam the next morning") to act as an explanation of the noun "priority."

INCORRECT EXPLANATIONS:

A semicolon connects two separate independent clauses, so that is incorrect.

Janine's priority is "studying," which is a gerund, so the past tense "studied" is incorrect.

The option that uses a comma is incorrect because the second clause is dependent and is lacking a subject.

The option that uses a colon unnecessarily includes the connector "and that was." These superfluous words cloud the sentence's meaning and make the sentence grammatically incorrect.

The phrasing of the sentence ("in previous decades") indicates that these were past "opportunities" that are presently available. This means that the present tense verb "are" in the underlined portion of the sentence needs to be changed to a past tense verb. Only one answer choice makes this change, "the organization provides opportunities that were not open," making it the correct answer choice.

The use of the present tense verb "believes" in the underlined portion of the sentence is at odds with the main verb of the sentence, "made," which is in the past tense. "Believes" needs to be changed to the past tense form, making "that the sergeant believed he would never" the correct answer choice.

The word "thinking" is acting like a participle in the original sentence, making the first clause lack a verb. Changing "Many parents mistakenly thinking" to "Many parents mistakenly think" corrects the sentence's error.