There are no errors in this sentence. The phrase "While many people picture ancient greek statues as the colorless marble we see today" 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. Furthermore, the phrase "in actuality" is an interjection or introductory phrase (to the following independent clause), which also needs to be separated from the main sentence with a comma. The correct choice is, "While many people picture ancient greek statues as the colorless marble we see today, in actuality, every bit of the statures were painted."

This sentence contains no errors. There is no need for punctuation because this is a simple sentence. Commas should not be placed between a verb and its object. The best choice is, "a person can have when investing is time."

There are no errors in this sentence. It is a simple sentence, so no punctuation is necessary. A comma is only present before conjunctions when the conjunction joins two independent clauses, which is not the case here. Additionally, commas never appear between a preposition and its object. The correct choice is, "Tesla is both the name of a man and a car."

The phrase "Because some of the investors were not happy with the CEO's pay" 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, as was done in the example sentence. The correct answer choice replicates the example sentence as it was written.

This sentence contains no error. The phrase "Though it requires a higher cost upfront" 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, "cost upfront, it is worth it to buy higher quality items over a long period of time."

This sentence contains no errors. The words "many" and "new" are coordinate adjectives: adjectives that modify the same noun separately, but are not separated with a conjunction. Coordinate adjectives need to be separated with a comma. The correct choice is, "The developers were building many, new neighborhoods near the city."

There are no errors in this sentence. The phrase "In the past century" 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.

Note that the choice with the phrasing "were not changed" is incorrect because it is in the passive voice, which is an unnecessary, if not strictly grammatically incorrect, change to make. Additionally, you do not need to rephrase the sentence to say that people changed engines, as the phrasing of this sentence is already correct and is - in fact - more concise. The correct answer choice is, "In the past century, engines have not changed."

This sentence does not contain any errors. The phrase "who would otherwise not have the opportunity" is an example of a relative clause, which gives more information about its antecedent: people. Any such phrase that occurs in the middle of a sentence must be introduced and completed with a comma. The correct choice is, "the Internet in the world is allowing many people, who would otherwise not have the opportunity, to share their experiences. "

This sentence contains no errors. This is a complex sentence with various clauses. The phrase "In addition to autonomous vehicles" 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.

"many companies are still working on alternative modes of transportation" is the main clause of this sentence. The following part, "such as flying cars, steam- or air-powered cars, and changes to current public transportation" is a parenthetical 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. Furthermore, the items in this expression are in a list, so they should be separated by commas.

Last, the word "steam-" should have the hyphen after it in order to indicate that it is part of the compound word "steam-powered." It is shorter alternative to saying "steam-powered and air-powered." Without the hyphen, the word "steam" should be treated as separate and unrelated to the word "air-powered," which then makes the phrase confusing.

The correct choice is, "many companies are still working on alternative modes of transportation, such as flying cars, steam- or air-powered cars, and changes to current public transportation."

This sentence contains no errors. The sentence combines two independent clauses with the use of the coordinating conjunction "but" and a comma. This is the correct usage. No other punctuation or changes are necessary. The correct choice is, "his inventions, but he was never satisfied with the end results."

Note that a single comma should not interrupt a clause, and that coordinating conjunctions cannot follow semicolons being used to join two independent clauses.