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."

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.

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 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.

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.

Because the event happens "tomorrow," in the future, the future tense needs to be used. "I have" is present tense, so changing "I have" to "I will have" changes it to the correct future tense.

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.

The sentence employs both the present-tense verb "make" and the past-tense verb "learned." Both of these verbs need to agree and employ the same tense. The only answer choice that correctly adjusts the tenses of the sentence's verbs is "Young professionals often make mistakes, but they also learn from them."

The progressive tense "filling" is correct here. This verb should be consistent with "burning," which precedes it in the list. Always think of descriptions of actions as scenes, and assess the logical viability of the scene painted (with grammar!). In this case, it doesn't really make sense that you would be "burning" the kernels but have "filled" the room with an odor since these two things occurred at the same time.