There's a long rant about "which" and "that" -- and why the difference really isn't important at all on the GMAT! -- in this post.

Here's a short preview:


For the rest of the post, please click here, and after reading it, you won't need to lose any more sleep thinking about this topic.

Enjoy!
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The most straightforward decision point here is meaning. If something dissipates, it disperses on its own -- like steam, for example.

If something is being dissipated, it sounds as though there's an outside force causing the dispersion -- a farmer spreading seeds, perhaps. In this case, we're talking about the acoustic energy of sound. It makes far more sense to write that this energy disperses on its own than that a third-party is sprinkling bits of sound through the air. Because "being dissipated" is illogical here, we can eliminate (D).

Note also, that "by" is a cleaner more concise way of expressing "as a result of." So while "as a result of" isn't inherently wrong, in a side-by-side comparison with "by," it's a clear loser.

I hope that helps!
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Hey GMATNinja, no further questions but ended up sitting the gmat today and came out with a 720 (v41) - thank you for the help and keep doing what you're doing!

Hi GmatNinja,

I'm facing trouble with this official question.

The increased popularity and availability of televisions has led to the decline of regional dialects, language variations which originate from diverse ethnic and cultural heritages and perpetuated by geographic isolation.


(A) which originate from diverse ethnic and cultural heritages and perpetuated

(B) that originated from diverse ethnic and cultural heritages and perpetuated

(C) originated from diverse ethnic and cultural heritages and perpetuated

(D) originating from diverse ethnic and cultural heritages and perpetuated

(E) originating from diverse ethnic and cultural heritages and perpetuating

I'm confused between C & D. I know the rule that in //ism, the modifiers can be in different form, however, I'm facing trouble recognizing why originated is not a modifier but verb ?

Thankyou!!

Yes, GMATPREP.

GMATNinja egmat daagh please help!

Hey,
if you marked B, then you are aware of most of the errors in other options : usage of "are" when subject is singular ("the discovery") and, "core, rotating ...." changes the meaning in a funny way.

But between, B and A
look at the last part of B) "and the formation and periodic reversal in direction of Earth's magnetic field"

This says that discovery is responsible for the "formation and periodic reversal in direction " .....

A discovery can't change something's direction ...
Therefore, A ) also with a parallel list of "of" is the right answer..

But I picked B), at first - just to tell you- you are not alone, its a tricky one.
Hope the experts clear more doubts, if any.

Fundamentally, I don't think there's anything wrong with using "that" to describe a person or people. So either of these are reasonable:

• "The man who consumed too much bourbon in his youth mistook his toddler for a stuffed ostrich."
• "The man that consumed too much bourbon in his youth mistook his toddler for a stuffed ostrich."

Both seem fine to me. Just as importantly, I've never seen an official GMAT SC question that forces you to choose between "who" and "that."

For whatever it's worth, "who" can be the beginning of either an essential or non-essential modifier:

• "The man who consumed too much bourbon in his youth mistook his toddler for a stuffed ostrich." -- Essential modifier: without the modifier, we apparently wouldn't know which man mistook his toddler for a stuffed ostrich.
• "The man, who consumed too much bourbon in his youth, mistook his toddler for a stuffed ostrich." -- Non-essential modifier: the part between the commas appears to be extra information, and without it, we'd still understand which man has problems recognizing his own kid.

As I've mentioned multiple times on this thread, the GMAT can't easily test the distinction between essential and non-essential modifiers, so I wouldn't worry about them too much.

I hope this helps!
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SC is less about why the correct answer is right than why the incorrect options are wrong. The key here, as Shrey9 notes below, is the parallel construction demanded by the multiple uses of "and," and how this construction shapes the meaning of the sentence.

First, take a look at (A), stripped down:

"The discovery [long modifier] is responsible for advancing studies of the flow of heat from the inner through the outer planet and of the formation and periodic reversal in direction of Earth's magnetic field."

Because "of the formation" ("preposition + noun") comes right after "and" we want a similar construction to precede it. In this case, we find "of the flow of heat." Now we want to ask ourselves if these two elements are logically parallel. And it makes perfect sense that the discovery is responsible for advancing studies of two things: (1) of the flow of heat and (2) of the formation and reversal of the earth's magnetic field. So keep (A).

Now compare that with all the other options. (B), (C), and (D) all lack the "of" before "formation." Is the preposition absolutely mandatory in a grammatical sense? No. But because the sentence is so complicated, it becomes very very difficult to see that the discovery is responsible for advancing studies of two separate elements if we don't include "of" before both of them. This confusion is enough to get rid of these options, but if you're skeptical, let's find a more concrete error in each:


Here, the "comma + and" creates the expectation that we're going to be treated to new information, potentially unrelated to what we've seen thus far. Put another way, it sounds as though "the discovery" is responsible only for advancing studies of how heat flows, and then there's this new clause about "the formation." But there's no verb to go with "formation!"

When we look back at the sentence, it appears that the discovery is responsible for "advancing studies" and for "the formation" itself. My physics is a little rusty, but I'm confident that a discovery can't be responsible for the formation of a magnetic field. That's illogical, so get rid of (B).

Both (C) and (D) have the same subject-verb agreement error: "The discovery... are responsible," so those are out.

And here's (E):
First, it sounds like the "earth's inner core" is itself responsible for advancing studies. Worse, there's no main verb here to go with the subject "the discovery." So this is illogical and ungrammatical. (E) is out, and (A) is our winner.

I hope that helps!
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Hi Charles,

I am going to give my GMAT exam in December. I have given three mock tests and in those, I have scored 590(Q40, V29-Official GMAT) in first, 560(Q33 V31) in second and 570(Q33,v31).
While I was analyzing these mocks, I scored poorly in SC and RC.
So can you pls suggest my a study plan for SC and RC for the next three month.What basics I need to cover and in how much time I should cover those topics
I have 3 hours to Study verbal on a weekday and 6 hours on weekends
I don't have any material right now except GMAT club SC book.

please help me in creating my study plan for the next three months

let me answer you quickly ..... I am sorry ninja !
if you see on gmat go for second Distinguish between x and y
according to Mgmat and og =
https://gmatclub.com/forum/in-his-resea ... 39274.html
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