The phrase "three years ago" indicates that the action of the sentence's action happened in the past. Despite this, the sentence is written with the present tense verb "deepens," leading to confusion with the timing of the sentence. "The mystery only deepened after the new evidence" is the only answer choice that features a past tense verb, so it is the only answer choice that clears up this confusion.

The use of the past tense verb "cleared" in the sentence is confusing and incorrect. "Cleared" is not the main verb in the sentence, and should take some other verbal form. Using the gerund, or a verb form that functions as a noun, the correct answer choice is "through the night clearing debris from the wreckage site."

The use of the present tense verb "create" is odd in this sentence, as the verb in the dependent clause is a past tense verb, "revolutionized." The two verbs should be in the same tense for the sentence to be logically correct. "The ancient Romans created a large network of paved roads" is the only answer choice to use the correct verb.

The use of "cause" to connect the dependent clause to the independent clause is confusing and incorrect. A partciple form, which can make the phrase a partcipal clause, would properly connect the action of the verb to the subject of the sentence. The only answer choice which properly uses the participle to make the dependent clause a grammatically correct participial clause is "The commander was horribly rude to his underlings, causing dissension in the ranks."

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 sentence uses present tense verbs, so "could not" must be present tense as well— that is, "cannot." Remember to check that verb tenses coordinate in a sentence!

The underlined words make up an incomplete verb phrase, as the verb "become" is in the wrong form. They appropriate version of "become" is the perfect tense, which indicates what has already happened. "Have become popular" is the correct answer choice.

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."

Although the verb is next to the singular noun "their father," the subject is actually compound, "The boys and their father," and therefore plural. The correct verb needs to be a plural form. "Eat" is the best choice among the answer choices.

The phrase "until they were changed" contains a past tense verb and indicates that the use of the present tense verb "prevent" is incorrect. "Prevent" needs to be changed to the past-tense "prevented" to make the sentence grammatically correct. "The arrangements prevented the groups from developing" is the only answer choice that uses the correct verb tense.