The improved sentence is better than the original because it cuts out unnecessary words, changing "or those who are lacking," to "or those who lack." This change also avoids having the same word next to itself, as was the case in "swimming, swimming." Although there was nothing grammatically wrong with this sentence, there was room for stylistic improvement, which was made. 

The best clue to the correct answer is the fact "of" is  not underlined, indicating the form must stay as "the use." The only issue is the form of "outlawing," which cannot be used with the subject of "the principal" as a verb on its own. "Outlawed the use" is the correct answer choice.

The underlined portion of the sentence has an odd verb usage in the word "involving." The sentence actually needs a past tense verb to make appropriate sense. "Was surprisingly involved" is the best choice among the answers.

The use of the word "attacking" is actually not a verb in the sentence, but a gerund, that is a verb form that can be used as a noun. The word needs to be turned into the appropriate verb form. "The sailors attacked their meal" is the correct answer choice.

The use of the verb "seeming" in the sentence makes the sentence incomplete. As "seeming" is a gerund, or a verb form that functions as a noun, there is actually no verb in the sentence. The correct answer is "seemed to get worse over time."

In most cases, the verb “to like” should be followed by an infinitive verb such as “to go” (e.g. "I really like to eat sushi."). "To have gone" and "going" are not appropriate here, nor are they in line with the meaning of the sentence, which expresses a regret.

The "waterfall" makes the "general" have a feeling of astonishment. The sentence as written makes this quite confusing. To make it correct grammatically, the form of the word needs to be something the general does. "Still astonished at the massive waterfall" is the correct answer choice.

The use of the verb form "sticking," a past participle," makes the action of the sentence unclear, as such forms usually need an extra verb to clarify the action. The verb form should be change to an active tense. Thus, "the painter stuck closely" is the correct answer choice.

The sentence as constructed does not actually contain a verb. "Having" in this sentence is the present participle, which always needs a form of the verb "to be." In this sentence, the appropriate form is "are," the plural form, making "The girls are having a party" the correct answer.

The use of "marching" makes the sentence not have a verb, as the participle form always needs some form of the verb "to be" used immediately before it to make it a complete verb. (For example, it's not grammatically correct to say "The fish swimming across the lake." Anyone who heard this might ask, "The fish swimming across the lake did what?" since "swimming" is a participle—a verb acting like an adjective. Instead, the correct way to say this would be, "The fish was swimming across the lake," or, alternatively, use a different verb form altogether, such as "The fish swam across the lake." To correct the problem's sentence, either the participle "marching" needs to be preceded by some form of the verb "to be," or it should be changed to some other form than the present participle to avoid functioning as an adjective and instead clearly function as the sentence's verb. The only answer choice that uses either of these options is "The battalion marches towards the battlefield on their way to the conflict."