GMAT Sentence Correction: How To Find the Core Sentence – Part 1

by on December 9th, 2014

verbalRecently, I was discussing sentence structure with one of my classes and we practiced a crucial but difficult GMAT skill: how to strip an SC sentence to its core components. Multiple OG problems can be solved just by eliminating faulty sentence cores—and the real GMAT is testing this skill today more than we see in the published materials.

So I’m going to write a series of articles on just this topic; welcome to part 1 (and props to my Wednesday evening GMAT Fall AA class for inspiring this series!).

Try out this GMATPrep® problem from the free exams. (Note: in the solution, I’m going to discuss aspects of our SC Process; if you haven’t learned it already, go read about it right now, then come back and try this problem.)

* “With surface temperatures estimated at minus 230 degrees Fahrenheit, Jupiter’s moon Europa has long been considered far too cold to support life, and with 60 square miles of water thought to be frozen from top to bottom.

“(A) Europa has long been considered far too cold to support life, and with

“(B) Europa has long been considered far too cold to support life, its

“(C) Europa has long been considered as far too cold to support life and has

“(D) Europa, long considered as far too cold to support life, and its

“(E) Europa, long considered to be far too cold to support life, and to have”

The First Glance does help on this one, but only if you have studied sentence structure explicitly. Before I did so, I used to think: “Oh, they started with Europa because they added a comma in some answers, but that doesn’t really tell me anything.”

But I’ve learned better! What is that comma replacing? Check it out: the first three answers all have a verb following Europa. The final two don’t; that is, the verb disappears. That immediately makes me suspect sentence structure, because a sentence does have to have a verb. If you remove a main verb from one location, you have to put one in somewhere else. I’ll be watching out for that when I read the sentence.

And now it’s time to do just that. As I read the sentence, I strip it down to what we call the “sentence core” in my mind. It took me a long time to develop this skill. I’ll show you the result, first, and then I’ll tell you how I learned to do it.

The “sentence core” refers to the stuff that has to be there in order to have a complete sentence. Everything else is “extra”: it may be important later, but right now, I’m ignoring it.

281 - image 1

I greyed out the portions that are not part of the core. How does the sentence look to you?

Notice something weird: I didn’t just strip it down to a completely correct sentence. There’s something wrong with the core. In other words, the goal is not to create a correct sentence; rather, you’re using certain rules to strip to the core even when that core is incorrect.

Using this skill requires you to develop two abilities: the ability to tell what is core vs. extra and the ability to keep things that are wrong, despite the fact that they’ll make your core sound funny. The core of the sentence above is:

Europa has long been considered too cold to support life, and.

Clearly, that’s not a good sentence! So why did I strip out what I stripped out, and yet leave that “comma and” in there? Here was my thought process:

Screen Shot 2014-12-08 at 10.06.34 AM

* Why isn’t estimated a verb?

Estimated is a past participle and can be part of a verb form, but you can’t say “Temperatures estimated at minus 230 degrees Fahrenheit.” You’d have to say “Temperatures are estimated at…” (Note: you could say “She estimated her commute to be 45 minutes from door to door.” In other words, estimated by itself can be the main verb of a sentence. In my example, though, the subject is actually doing the estimating. In the GMATPrep problem above, the temperatures can’t estimate anything!)

** Why is it that I expected another complete sentence to follow the “comma and”?

The word and is a parallelism marker; it signals that two parts of the sentence need to be made parallel. When you have one complete sentence, and you follow that with “comma and,” you need to set up another complete sentence to be parallel to that first complete sentence.

For example:

She studied all day, and she went to dinner with friends that night.

The portion before the and is a complete sentence, as is the portion after the and.

(Note: the word and can connect other things besides two complete sentences. It can connect other segments of a sentence as well, such as: She likes to eat pizza, pasta, and steak. In this case, although there is a “comma and” in the sentence, the part before the comma is not a complete sentence by itself. Rather, it is the start of a list.)

Okay, so my core is:

Europa has long been considered too cold to support life, and.

And that’s incorrect. Eliminate answer (A). Either that and needs to go away or, if it stays, I need to have a second complete sentence. Since you know the sentence core is at issue here, check the cores using the other answer choices:

281 - image 2

Here are the cores written out:

“(B) Europa has long been considered too cold to support life.

“(C) Europa has long been considered as too cold to support life and has 60 square miles of water.

“(D) Europa and its 60 square miles of water.

“(E) Europa.”

(On the real test, you wouldn’t have time to write that out, but you may want to in practice in order to build expertise with this technique.)

Answers (D) and (E) don’t even have main verbs! Eliminate both. Answers (B) and (C) both contain complete sentences, but there’s something else wrong with one of them. Did you spot it?

The correct idiom is consider X Y: I consider her intelligent. There are some rare circumstances in which you can use consider as, but on the GMAT, go with consider X Y. Answers (C), (D), and (E) all use incorrect forms of the idiom.

Answer (C) also loses some meaning. The second piece of information, about the water, is meant to emphasize the fact that the moon is very cold. When you separate the two pieces of information with an and, however, they appear to be unrelated (except that they’re both facts about Europa): the moon is too cold to support life and, by the way, it also has a lot of frozen water. Still, that’s something of a judgment call; the idiom is definitive.

The correct answer is (B).

Go get some practice with this and join me next time, when we’ll try another GMATPrep problem and talk about some additional aspects of this technique.

Key Takeaways: Strip the sentence to the Core

(1) Generally, this is a process of elimination: you’re removing the things that cannot be part of the core sentence. With rare exceptions, prepositional phrases typically aren’t part of the core. I left the prepositional phrase of water in answers (C) and (D) because 60 square miles by itself doesn’t make any sense. In any case, prepositional phrases never contain the subject of the sentence.

(2) Other non-core-sentence clues: phrases or clauses set off by two commas, relative pronouns such as which and who, comma + -ed or comma + ing modifiers, -ed or –ing words that cannot function as the main verb (try them in a simple sentence with the same subject from the SC problem, as I did with temperatures estimated…)

(3) A complete sentence on the GMAT must have a subject and a working verb, at a minimum. You may have multiple subjects or working verbs. You could also have two complete sentences connected by a comma and conjunction (such as comma and) or a semi-colon. We’ll talk about some additional sentence structures later in this series.

* GMATPrep® questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.


  • I understand that it's B as it is the best of the worst, but I cannot seem to justify in my mind "Europa has long been considered far too cold to support life, its 60 square miles of water thought to be frozen from top to bottom." Shouldn't there be a verb before "thought?" It seems incomplete. How can I think of this differently?

    • KrisH, I´m with you. Had the same question... I ruled out choice B because of the last word "it"... it didn´t make much sense.

  • Dear Stacey,

    The article, as always all yours posts, has taught me a very important lesson. Just to clarify, I need to ask one question regarding the nature of the modifier in the example sentence - "its 60 square miles of water thought to be frozen from top to bottom". The modifier is separated from the core of the sentence by a comma. It has phrases, which include a pronoun "its" and participial phrase "thought", that seem to modify entire clause preceding it and providing more information describing how cold was Europa.

    Kindly elaborate.  

  • Hi Stacey. I believe you have made a mistake in your explanation. "Its" and "thought" without to-be? The M-W dictionary has this section on grammar basics that completely contradicts what is written here. 

    Please provide more explanation on why you think your answer still holds.

  • Hi, everyone! Lots of questions on this one.

    I'll start at the end: Ethan, this is an official question; it was once given on the GMAT. In other words, answer (B) is the official correct answer to an official question; that construction is 100% valid.

    (I do just want to make sure you were reading the problem correctly. Your post seems to imply that the correct answer is missing the "to be" portion of "thought to be." In fact, the correct answer does say "thought to be.")

    Okay, the part after the comma does *sound* weird, because we would never speak that way in real life (and most people wouldn't write that way). It's really just an adverbial modifier, though. (Arun, you're right! Nice job!)

    Here's a simpler example of the same type of construction:
    The abandoned cat meowed forlornly, its fur matted into clumps.

    Poor cat! The core sentence is before the comma. The part after is a modifier providing extra information about this abandoned cat who seems lost and sad. Note that this is an adverbial modifier: it's not just providing extra info about the cat, it's providing extra info about the entire state of the cat (that is, the main clause / sentence).

    The construction in the GMATPrep question above is identical - just more complicated:
    Europa has been considered too cold to support life, its water thought to be (completely) frozen.

    Again, we've got a modifier that is providing additional info not just about the noun Europa but about the entire main clause: Europa is so very cold that we think it can't support life.

Ask a Question or Leave a Reply

The author Stacey Koprince gets email notifications for all questions or replies to this post.

Some HTML allowed. Keep your comments above the belt or risk having them deleted. Signup for a Gravatar to have your pictures show up by your comment.