The use of "him" in the subject of a sentence is incorrect, as "him" is the objective third person pronoun. The pronoun needs to be changed to a subjective pronoun because it appears in the subject of the sentence. The only answer choice that takes care of this problem is "They had known each other for years."

The use of "me" as the subject of a sentence is incorrect, as "me" is an objective pronoun and should only be used as the object of a sentence. The only answer choice that takes care of this pronoun issue is "My little sister and I have always had trouble getting along with each other.

The use of "I" as the object of the sentence is incorrect, as it can only be used as the subject of a sentence. The pronoun needs to be changed to the objective pronoun form, "me." The only answer choice which uses this form of the pronoun is "has been reviewed by the president and me."

This sentence contains an error in pronoun case. Because "I" is found in a prepositional phrase and is not the subject, it should be changed to "me." Two choices correct this, but one of them creates a clarity problem by changing the word order.

Both "me" and "him" are objective pronouns, and as such can only be used as objects; however, in this sentence, they are the subjects. The proper subject forms are "he" and "I," and should be used accordingly. The correct answer is "He and I were."

Because both pronouns are used as subjects of the sentence, "me and her" is incorrect, as they are objective pronouns being used where subjective pronouns are needed. "She and I were going to see" is the only answer choice that uses the right pronouns, so it is the correct answer.

The pronoun "us" in the sentence is a subject complement, because it follows the linking verb "is" and renames the subject "it" in more detail. Pronouns used as subject complements need to be in the subjective form, just like the subjects of sentences. "Us" is the objective form of the first-person plural pronoun, so it is incorrect. Changing "us" to "we," the subjective form of the first-person plural pronoun, corrects the sentence's error. The corrected sentence reads, "Even though Jack took the credit for returning the lost puppy, most of the neighborhood knew it was actually we who did the good deed."

The use of "I" as the object of the prepositional phrase "by the author and I" is incorrect, as "I" is the subjective form of the first person pronoun. To correct the sentence's error, "I" must be replaced by the objective form of the first person pronoun, "me." Therefore, the correct answer choice is "by the author and me."

Only the answer choice "she had decided to dedicate her latest novel to their daughter and him until it was published" correctly uses the pronoun "him," which is the objective case pronoun, as an object of the preposition "to."

All of the other answer choices use the pronoun "he," which is the subjective case pronoun, instead of "him," and are therefore incorrect.

The underlined portion of the sentence has an issue with the word "cities." The word is actually used as a possessive, instead of the plural form that is written in the sentence. The appropriate form is "of the city's skyline."