“Believing” would constitute an incorrect gerund usage. “Me” must be changed to “I” because it is the nominative case pronoun.

The first person pronoun in this sentence is the object of the preposition "to," and should therefore be in objective case. "Me" is the appropriate choice instead of "I." To simplify, you can remove Kathy momentarily (sorry, Kathy!) and see how the sentence would sound in a simpler form. "...was assigned to I" doesn't sound right, so "...was assigned to Kathy and I" shouldn't be right, either.

The first person pronoun should be the objective case "me" as opposed to the subjective "I." If we remove "Will" from the sentence and simplify by removing the modifier offset by commas, we get the super-simple: "The manager offered I a half-hearted explanation." This illustrates the benefit of the simplifying tip, which can point out sentence flaws that become shrouded as complexity increases.

The sentence misuses the word "who." "Who" is only used when it is the subject of a clause, but it is acting as the object the clause "everyone liked," so the appropriate choice is "whom." All other punctuation is already correct, so the best choice is, "The new boss, whom everyone liked, made many changes that led to a better working environment."

This sentence contains a misuse of the word "whom." "Whom" is only used when it functions as the object of a verb or preposition in a clause, but it is clear that whatever word should be in this position is acting as the subject of the clause in this sentence. The appropriate answer is "who" because the pronoun is acting as the subject of the clause and is referring to people. The correct answer is "who."

This sentence uses the wrong form of "who." It is clear that "that" and "which" are not appropriate, because Joshua is a human. The pronoun "who" is not the subject of the relative clause; however, the "who" is being liked, not doing the liking. When it is not the subject of the clause, the appropriate form is "whom." The correct choice is, "whom."

This sentence uses the wrong case of "he" and "I." Think about it: if these pronouns were in separate sentences, you would not say "to he" or "to I." You give a gift "to him" or "to me." Furthermore, the first person pronoun (I/me) should always come after other pronouns in a group. The correct choice is, "to him and me."

This sentence uses the wrong pronoun. "We" is always the subject of a clause; the correct form here is "us." The correct choice is "My mother told us to play outside" because it is the most concise option that fixes this issue. "We were told by my mother to play outside" is technically grammatically correct, but it is unnecessarily in the passive voice, and thus obviously a less concise choice than the correct answer option.

This sentence misuses the word "me." Rephrasing the sentence a bit, "Me went to the park" does not make much sense. "Me" is only used when it is the object of another word (verb, preposition, etc.). The correct form is "I;" the other choices make no sense because it changes the meaning of the sentence. The correct choice is, "My friend and I went."

This sentence contains two error: misuse of the pronoun "who" and a dangling preposition (from). First, the relative clause could be rephrased as "I borrowed the movie from her. The word "her" functions as the object in this phrase, so, likewise, "who" should function as the object in the relative clause. "Who," though, is always the subject of a sentence; the correct form is "whom." Furthermore, prepositions should never end a clause; it would be most appropriate for the from to appear before "whom." The correct choice is, "from whom I borrowed the movie."