This sentence does not contain a comma where necessary. The phrase "While he completed the test" is an example of an introductory phrase, explaining information necessary to the context of the sentence, but outside of the main sentence, grammatically. These types of phrases must be followed by a comma in order to separate them from the rest of the sentence. The correct answer choice is, "While he completed the test, he forgot."

This sentence does not contain commas where they are necessary. The phrase "such as sleeping and eating well" is a paranthetical expression: a phrase that explains more about a particular word or phrase in the sentence, but is not introduced by a relative pronoun. These phrases must be introduced and completed with a comma in order to separate them from the main clause of the sentence. The correct answer choice is, " things, such as sleeping and eating well, can have a huge impact."

This sentence does not contain a comma where one is necessary. The phrase "After much practice" is an example of an introductory phrase, explaining information necessary to the context of the sentence, but outside of the main sentence, grammatically. These types of phrases must be followed by a comma in order to separate them from the rest of the sentence. The correct answer choice is, "After much practice, Tammy's tennis game."

This sentence does not contain a comma where one is necessary. Since this is a direct quote, a comma should appear after the word "said." Note that Double quotations must be used (single quotations are only used when a quote appears within an already existing quote). The correct choice is, "Michael Dell said, "You don't have to be a genius or a visionary or even a college graduate to be successful."

This sentence does not contain a comma where one is necessary. The phrase "Because of her promotion" is an example of an introductory phrase, explaining information necessary to the context of the sentence, but outside of the main sentence, grammatically. These types of phrases must be followed by a comma in order to separate them from the rest of the sentence. The correct answer choice is, "Because of her promotion, Heidi was moving."

This sentence does not contain a comma where necessary. The phrase "Surprisingly" is an example of an introductory phrase, explaining information necessary to the context of the sentence, but outside of the main sentence, grammatically. These types of phrases must be followed by a comma in order to separate them from the rest of the sentence. The correct answer choice is, "Surprisingly, he managed to win the contest."

This sentence contains a comma where one is not necessary. Commas are generally used to separate clauses, but the word "ever" is in the same clause as "written," and they are not coordinate adjectives. The comma should be omitted. Note that no additional punctuation is necessary because prepositional phrases do not start new clauses, which is necessary for the use of any of the punctuation present in the above choices (commas, colons). The correct choice is, "the longest books ever written in history."

This sentence does not contain commas where they are necessary. The phrase "who completed the challenge faster than anyone else" is an example of a relative clause, which gives more information about its antecedent: Sharon. Any such phrase that occurs in the middle of a sentence must be introduced and completed with a comma. The correct answer choice is, "Sharon, who completed the challenge faster than anyone else, would."

This sentence contains a comma where one is not necessary. Commas should only appear before conjunctions when that conjunction joins two independent clauses. The word "bleak" is not an independent clause. The correct choice is, "was short and bleak."

This sentence misuses the comma before "and." Commas should only appear before conjunctions when the conjunction joins two independent clauses. The clause "prepared to leave for the airport" cannot be an independent clause, however, because it does not contain a subject. If a "he" were added before the word "prepared," the comma would be fine. The correct choice is, "He packed his bags and prepared."