GMAT Sentence Correction: How To Find the Core Sentence - Part 4
Its here at last: the fourth and final installment of our series on core sentence structure!
I recommend reading all of the installments in order,part 1, part2, respectively part 3.
Try out this GMATPrep problem from the free exams.
* The greatest road system built in the Americas prior to the arrival of Christopher Columbus was the Incan highway, which, over 2,500 miles long and extending from northern Ecuador through Peru to southern Chile.(A) Columbus was the Incan highway, which, over 2,500 miles long and extending
(B) Columbus was the Incan highway, over 2,500 miles in length, and extended
(C) Columbus, the Incan highway, which was over 2,500 miles in length and extended
(D) Columbus, the Incan highway, being over 2,500 miles in length, was extended
(E) Columbus, the Incan highway, was over 2,500 miles long, extending
The First Glance in this question is similar to the one from the second problem in the series. Here, the first two answers start with a noun and verb, but the next three insert a comma after the subject. Once again, this is a clue to check the core subject-verb sentence structure.
First, strip down the original sentence:
Heres the core:
The greatest road system was the Incan highway.
(Technically, greatest is a modifier, but Im leaving it in because it conveys important meaning. Were not just talking about any road system. Were talking about the greatest one in a certain era.)
The noun at the beginning of the underline, Columbus, is not the subject of the sentence but the verb was does turn out to be the main verb in the sentence. The First Glance revealed that some answers removed that verb, so check the remaining cores.
(B) The greatest road system was the Incan highway and extended from Ecuador to Chile.(C) The greatest road system.
(D) The greatest road system was extended from Ecuador to Chile.
(E) The greatest road system was over 2,500 miles long.
Answer (C) is a sentence fragment; it doesnt contain a main verb. The other choices do contain valid core sentences, though answers (B) and (D) have funny meanings. Lets tackle (B) first.
(B) The greatest road system was the Incan highway and extended from Ecuador to Chile."
When two parts of a sentence are connected by the word and, those two parallel pieces of information are not required to have a direct connection:
Yesterday, I worked for 8 hours and had dinner with my family.
Those things did not happen simultaneously. One did not lead to the other. They are both things that I did yesterday, but other than that, they dont have anything to do with each other.
In the Columbus sentence, though, it doesnt make sense for the two pieces of information to be separated in this way. The road system was the greatest system built to that point in time because it was so long. The fact that it extended across all of these countries is part of the point. As a result, we dont want to present these as separate facts that have nothing to do with each other. Eliminate answer (B).
Now, lets take a look at (D). Whats the difference in meaning between these two sentences:
"(D) The greatest road system was extended from Ecuador to Chile.
alternative: The greatest road system extended from Ecuador to Chile.
In my alternative example, the sentence indicates that the system went from one country to another and this is part of the reason it was the greatest road system at one point in time. This is the logical meaning, so the alternative example works.
Answer (D), by contrast, indicates that the road was first built (and considered the greatest system of that time), and then at some later time, the road system was extended even further. Combine this with the modifier about the actual length of the road. When was the system over 2,500 miles in length: when it was first built or after it was extended? Its unclear. (And, more logically, its probably the case that it didnt earn the designation of greatest road system until after it was built out from Ecuador to Chilein other words, were probably not talking about two different timeframes here. Indeed, three of the answers do convey that the road earned the designation as the greatest system in part because of this Ecuador-to Chile portion.)
What next? Were down to (A) and (E).
It turns out that certain modifiers are also required to be clauses. (A clause is the official grammar term for a set of words that includes a conjugated or tensed verb.) Every sentence is required to contain at least one independent clause, but sentences can also contain dependent clauses, which provide extra information about something else in the sentence.
Take a look at this example:
Each December, the company releases its annual report, which summarizes major accomplishments from the past year.
The core sentence is the portion before the comma. The comma which structure introduces a modifier describing the annual report: the annual report summarizes major accomplishments from the past year. The word summarizes is a tensed verb or conjugated verb, but it is not acting as a main verb in the sentence. Rather, it is strictly providing extra information about something in the core of the sentence (the annual report).
Even though the comma which modifier is just extra information in the sentence, it does need to contain a tensed verb. Any modifier introduced by a relative pronoun has to contain a tensed verb. (Some examples of relative pronouns are which, who, that*, whom, whose.)
*Note: the word that is flexible; it can play multiple roles in a sentence. In addition to acting as a relative pronoun, it can also be used in the Subject-Verb-THAT structure that we examined in the third installment of this series. (That can also be used in other waysbut this article is not about that topic.) (See what I did there? I showed you a third way that that can be used.)
You may already have spotted that the original sentence contained an error related to this requirement that the comma which modifier has to contain a tensed verb. Heres the modifier from the original sentence:
the Incan highway, which, over 2,500 miles long and extending from northern Ecuador through Peru to southern Chile.
The portion over 2,500 miles long doesnt contain a verb. The next portion, beginning extending from, may appear to contain a verb, but this is not a sentence: The highway extending from X to Y. You would need to say something like The highway extended from X to Y.
In other words, answer (A) contains a faulty clause; the comma which modifier is missing its tensed verb. Weve now eliminated (A), (B), (C), and (D).
The correct answer is (E).
Key Takeaways: Strip the sentence to the Core
(1) Sometimes, modifiers are required to have a tensed verb, too, as in answer (A) above. If the modifier is missing this verb, the construction is incomplete and the sentence is wrong. You can learn more about the types of modifiers that require tensed verbs in the Modifiers chapter of our Sentence Correction Strategy Guide.
(2) Both sentence structure and modifiers are tightly tied to meaning. A sentence may be constructed acceptably on a purely technical level and still have meaning issues, as we saw in answers (B) and (D) above.
(3) Now we come full circle: a sentence still has to be a sentence. If the main verb doesnt exist, that answer choice has to be wrong, as in answer (C). This may seem like a no-brainer rule, but GMAT sentences are often so convoluted that it can be easy to overlook the fact that a verb is missing. Keep training yourself to look for the core sentence!
* GMATPrep questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.