This sentence contains a colon where one is not necessary. Colons are used to join two clauses when the second clause explains something about the first clause. Colons are not used with conjunctions like "because," though. Furthermore, the word "because" does not need a comma before it (only coordinating conjunctions need a comma before it when joining an independent clause to another. The correct choice is, "The teacher's rates were high because his students."

This sentence contains an error in the usage of the colon. Colons are used to join two clauses when the second clause explains something in the first clause. The colons in the choices above, however, only split up the existing clauses (Colons never are used in the middle of clauses and absolutely never after a preposition like "of"). The best choice is to omit the colon. The correct answer is, " in order to achieve his goal of becoming a pro skater."

This sentence misuses the colon. Colons are used to join two clauses (the first one has to be independent) when the second clause explains/describes something about the first clause. In the above choices, the colon does not appear in any place between clauses. The correct choice is, "He always appreciated a pen that wrote well."

This sentence does not contain a colon where necessary. The phrase "The Grapes of Wrath, Animal Farm, and To Kill A Mockingbird" describe exactly what books the subject plans to read. Colons should be used when combining two related clauses when the second clause explains something about the first one; therefore, a colon should appear after the word "vacation." The correct choice is, "books during his vacation: The Grapes of Wrath, Animal Farm, and To Kill A Mockingbird."

This sentence has misplaced the colon. The colon should come after the word "include" since that word marks the end of the first clause. Note that colons combine two clauses when the second one explains or describes something about the first clause. The correct choice is, "market caps on the stock market include: Roundree, Gargle, and Mousecow."

This sentence uses a colon where one is not necessary. Colons are used to join two clauses when the second clause describes something about the first clause. In this sentence, however, there is only one clause (the word "that" does not begin a new clause, but an indirect statement phrase). The correct choice is, "that he was going in the wrong direction."

This sentence contains an error in the placement of the colon. Colons are used to join two clauses when the second clause explains something about the first clause. In this sentence, however, there is only one clause (colons never split clauses). It is best to omit the colon. The correct choice is, "newest creation was incredibly delicious."

This sentence contains a colon where a semicolon is necessary. Colons join two related clauses when the second one explains something about the preceding clause. In this sentence, however, the phrase "so far, he had shaved one minute off of his time per mile" does not explain why the subject tries to improve his timing or how he goes about doing that; it simply tells us his progress in this endeavor. Semicolons join two related independent clauses without the use of a conjunction. This is the appropriate choice. The correct answer is, "improve his running time; so far, he had shaved."

This sentence contains a colon where a comma is necessary. The phrase "In the past" 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, "In the past, many civilizations have looked."

This sentence uses a colon where one is not necessary. Colons are used to join clauses when the second clause explains something about the first one. In this sentence, however, the colon appears in the midst of the clause, before a preposition. Colons should never be used in this way (never in conjunction with a preposition). The correct choice is, "the weekdays when less people were in the stores."