Final answer:
The colon is used correctly in the given sentence to introduce a list that elaborates on why Lydia is considered the best friend. Colons are meant to introduce lists, summaries, quotations, or to connect two independent clauses where the second emphasizes the first.
Step-by-step explanation:
In the sentence provided, the colon usage is correct. The independent clause before the colon is 'Lydia is definitely my best friend,' which is followed by a list that expands on why she is considered the best friend. This is precisely the function of a colon, as indicated by rule 11.4, to provide a list, quotation, or related idea after an independent clause.
To further illustrate how colons can be used effectively, let's review the sentence 'Successful athletes have the following qualities: physical ability, mental toughness, commitment, and optimism.' The colon is correctly used to introduce a list that is directly related to the independent clause preceding it, which fulfills the condition of emphasizing the second clause or presenting a list pertinent to the first.
As for the review questions, let's insert the necessary commas: I finally found my keys, and I got to work just in time. Mrs. Contreras threw out her old coffee table and cleaned the carpet. Taking the elevator to the roof, we hoped we could see the skyline and the bay. Though Susan wasn't feeling well, she went to the store anyway and bought ice cream, pizza, and candy. I let my neighbor borrow my phone because she said hers was tapped by the police.