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## To map Earth's interior, geologists use a network

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richachampion Legendary Member
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#### To map Earth's interior, geologists use a network

Tue Jul 21, 2015 2:43 am
To map Earth's interior, geologists use a network of seismometers to chart seismic waves that originate in the earth's crust and ricochet around its interior, most rapidly traveling through cold. dense regions and slower through hotter rocks.

A. interior, most rapidly traveling through cold, dense regions and slower
B. interior, which travel most rapidly through cold, dense regions, and more slowly
C. interior, traveling most rapidly through cold, dense regions and more slowly
D. interior and most rapidly travel through cold, dense regions, and slower
E. interior and that travel most rapidly through cold, dense regions and slower

OA: C

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Mon Jul 04, 2016 5:22 am
Crystal W wrote:
I am a little confused about choice C and choice E. I understand most rapidly and slower are not parallel in E. OG said "The action, ricochet, is further described in a participial phrase in which traveling...is then further described in a comparison of travel speeds in cold and hot regions of Earth's crust." I don't agree with it and I think two that-clauses in E are parallel and they all modify seismic waves. In choice C, the structure is "Clause + Comma + Travelling" and I think travelling ... modifies the subject of previous clause -- seismic waves. Am I correct or someone can correct me?
E: seismic waves that originate in the earth's crust and ricochet around its interior and that travel most rapidly through cold, dense regions
Here, the that-modifier in red serves to refer to seismic waves.
Its role is purely adjectival, describing the KIND of seismic waves under discussion.
What KIND of seismic waves?
Seismic waves THAT TRAVEL MOST RAPIDLY THROUGH COLD, DENSE REGIONS.

OA: seismic waves that originate in the earth's crust and ricochet around its interior, traveling most rapidly through cold, dense regions
Here, the COMMA + VERBing modifier in red serves to refer both to the preceding ACTION (ricochet) and to the agent of this action (seismic waves).
Unlike a that-modifier -- whose function is purely adjectival -- a COMMA + VERBing modifier plays both an adjectival and an ADVERBIAL role.
As an adjective, it describes the agent of the preceding action.
As an adverb, it serves to express an action happening AT THE SAME TIME AS or AS A DIRECT RESULT OF the preceding action.
In the OA, one function of COMMA + traveling is to serve as an ADJECTIVE describing the KIND of seismic waves under discussion.
What KIND of seismic waves?
Seismic waves TRAVELING MOST RAPIDLY THROUGH COLD, DENSE REGIONS.
However, COMMA + traveling is also an ADVERB modifying the preceding action -- ricochet -- since the act of TRAVELING happens as a direct result of this action.
For this reason, COMMA + traveling can be said to describe HOW seismic waves RICOCHET.

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Crystal W Master | Next Rank: 500 Posts
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Sun Jul 03, 2016 6:02 pm
I am a little confused about choice C and choice E. I understand most rapidly and slower are not parallel in E. OG said "The action, ricochet, is further described in a participial phrase in which traveling...is then further described in a comparison of travel speeds in cold and hot regions of Earth's crust." I don't agree with it and I think two that-clauses in E are parallel and they all modify seismic waves. In choice C, the structure is "Clause + Comma + Travelling" and I think travelling ... modifies the subject of previous clause -- seismic waves. Am I correct or someone can correct me?

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Wed Jul 22, 2015 3:08 am
richachampion wrote:
To map Earth's interior, geologists use a network of seismometers to chart seismic waves that originate in the earth's crust and ricochet around its interior, most rapidly traveling through cold. dense regions and slower through hotter rocks.

A. interior, most rapidly traveling through cold, dense regions and slower
B. interior, which travel most rapidly through cold, dense regions, and more slowly
C. interior, traveling most rapidly through cold, dense regions and more slowly
D. interior and most rapidly travel through cold, dense regions, and slower
E. interior and that travel most rapidly through cold, dense regions and slower
A, D and E: cold, dense regions and slower
Here, a reader might construe that slower is an ADJECTIVE intended to be parallel with cold and dense (both adjectives).
The intended meaning is for slower to serve as an ADVERB modifying traveling.
B and C convey this meaning more clearly by using the parallel forms most rapidly and more slowly:
MOST RAPIDLY through cold, dense regions and MORE SLOWLY through hotter rocks.
Eliminate A, D and E.

The referent for which + PLURAL VERB must be the NEAREST PRECEDING PLURAL NOUN.
B: waves that originate...which travel
Here, which travel (which + PLURAL VERB) seems to refer to waves (the nearest preceding plural noun).
As a result, that and which both have the same referent (waves).
Two different pronouns cannot have the same referent.
Eliminate B.

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OptimusPrep Master | Next Rank: 500 Posts
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Thu Jul 23, 2015 7:54 pm
A.interior, most rapidly traveling through cold, dense regions and slower
"cold, dense" are modifying regions and slower is modifying travel. These adjectives cannot be a part of a list as they are modifying different things.
B.interior, which travel most rapidly through cold, dense regions, and more slowly
Here the referrent of the pronoun which is unclear.
C.interior, traveling most rapidly through cold, dense regions and more slowly
Correct
D.interior and most rapidly travel through cold, dense regions, and slower
"cold, dense" are modifying regions and slower is modifying travel. These adjectives cannot be a part of a list as they are modifying different things.
E.interior and that travel most rapidly through cold, dense regions and slower
"cold, dense" are modifying regions and slower is modifying travel. These adjectives cannot be a part of a list as they are modifying different things.

Pal22 Newbie | Next Rank: 10 Posts
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Fri Oct 23, 2015 7:31 am
Hi GMATGuruNY,

Please can you help elaborate on the rule - "Two different pronouns cannot have the same referent.". Are there other examples that you can also share please?

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Fri Oct 23, 2015 7:52 am
Pal22 wrote:
Hi GMATGuruNY,

Please can you help elaborate on the rule - "Two different pronouns cannot have the same referent.". Are there other examples that you can also share please?
B implies the following:
waves that originate in originate in the earth's crust
waves, which travel most rapidly through cold, dense regions

The pronouns in red both seem to refer to waves.
Two different pronouns -- in this case, that and which -- cannot have the same referent.

Other examples:
http://www.beatthegmat.com/gprep-sc-17-t277559.html
http://www.beatthegmat.com/the-scandinavian-assault-on-western-europe-culminated-in-the-t286698.html

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ngk4mba3236 Master | Next Rank: 500 Posts
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Tue Mar 29, 2016 3:40 am
GMATGuruNY wrote:
B implies the following:
waves that originate in originate in the earth's crust
waves, which travel most rapidly through cold, dense regions

The pronouns in red both seem to refer to waves.
Two different pronouns -- in this case, that and which -- cannot have the same referent.
have a quick question --

in GMAT, that and which clause can't be connected by conjunction and and hence can't be VALID parallel structure. am i correct ?

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Sat Apr 02, 2016 3:09 am
ngk4mba3236 wrote:
GMATGuruNY wrote:
B implies the following:
waves that originate in originate in the earth's crust
waves, which travel most rapidly through cold, dense regions

The pronouns in red both seem to refer to waves.
Two different pronouns -- in this case, that and which -- cannot have the same referent.
have a quick question --

in GMAT, that and which clause can't be connected by conjunction and and hence can't be VALID parallel structure. am i correct ?
This line of reasoning is valid.

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Needgmat Master | Next Rank: 500 Posts
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Tue Jun 28, 2016 10:43 am
Hi GMATGuruNY ,

I have a two questions:

1) Can you please explain that in OA HOW and WHAT COMMA+VERBing(TRAVELLING) refers to?

2) Can you please explain more about that and which clause can't be connected by conjunction and and hence can't be VALID parallel structure.

Thanks,

Kavin

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Wed Jun 29, 2016 5:32 am
Needgmat wrote:
Can you please explain that in OA HOW and WHAT COMMA+VERBing(TRAVELLING) refers to?
Generally, COMMA + VERBing serves to refer to the agent of the NEAREST PRECEDING ACTION.
OA: waves that...ricochet around its interior, traveling most rapidly through cold, dense regions.
Here, the action that most closely precedes COMMA + traveling is ricochet.
Thus, traveling serves to refers to waves, the agent of this action.
Conveyed meaning:
As waves RICOCHET, they are at the same time TRAVELING.

Quote:
2) Can you please explain more about that and which clause can't be connected by conjunction and and hence can't be VALID parallel structure.
Parallel forms must serve the SAME FUNCTION.
A that-modifier is an ESSENTIAL MODIFIER: one that is necessary to convey the intended meaning of the sentence.
A which-modifier is a NONESSENTIAL MODIFIER: one that can be removed without altering the basic meaning of the sentence.
Since a that-modifier and a which-modifier serve different functions, they cannot be connected by a conjunction such as and.

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Needgmat Master | Next Rank: 500 Posts
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Fri Jul 01, 2016 10:40 pm
Quote:
GMATGuruNY wrote:
Needgmat wrote:
Can you please explain that in OA HOW and WHAT COMMA+VERBing(TRAVELLING) refers to?
Generally, COMMA + VERBing serves to refer to the agent of the NEAREST PRECEDING ACTION.
OA: waves that...ricochet around its interior, traveling most rapidly through cold, dense regions.
Here, the action that most closely precedes COMMA + traveling is ricochet.
Thus, traveling serves to refers to waves, the agent of this action.
Conveyed meaning:
As waves RICOCHET, they are at the same time TRAVELING.

Quote:
2) Can you please explain more about that and which clause can't be connected by conjunction and and hence can't be VALID parallel structure.
Parallel forms must serve the SAME FUNCTION.
A that-modifier is an ESSENTIAL MODIFIER: one that is necessary to convey the intended meaning of the sentence.
A which-modifier is a NONESSENTIAL MODIFIER: one that can be removed without altering the basic meaning of the sentence.
Since a that-modifier and a which-modifier serve different functions, they cannot be connected by a conjunction such as and.
Hi GMATGuruNY ,

Thanks,

Kavin

Crystal W Master | Next Rank: 500 Posts
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Mon Jul 04, 2016 5:31 am
GMATGuruNY wrote:
Crystal W wrote:
I am a little confused about choice C and choice E. I understand most rapidly and slower are not parallel in E. OG said "The action, ricochet, is further described in a participial phrase in which traveling...is then further described in a comparison of travel speeds in cold and hot regions of Earth's crust." I don't agree with it and I think two that-clauses in E are parallel and they all modify seismic waves. In choice C, the structure is "Clause + Comma + Travelling" and I think travelling ... modifies the subject of previous clause -- seismic waves. Am I correct or someone can correct me?
E: seismic waves that originate in the earth's crust and ricochet around its interior and that travel most rapidly through cold, dense regions
Here, the that-modifier in red serves to refer to seismic waves.
Its role is purely adjectival, describing the KIND of seismic waves under discussion.
What KIND of seismic waves?
Seismic waves THAT TRAVEL MOST RAPIDLY THROUGH COLD, DENSE REGIONS.

OA: seismic waves that originate in the earth's crust and ricochet around its interior, traveling most rapidly through cold, dense regions
Here, the COMMA + VERBing modifier in red serves to refer both to the preceding ACTION (ricochet) and to the agent of this action (seismic waves).
Unlike a that-modifier -- whose function is purely adjectival -- a COMMA + VERBing modifier plays both an adjectival and an ADVERBIAL role.
As an adjective, it describes the agent of the preceding action.
As an adverb, it serves to express an action happening AT THE SAME TIME AS or AS A DIRECT RESULT OF the preceding action.
In the OA, one function of COMMA + traveling is to serve as an ADJECTIVE describing the KIND of seismic waves under discussion.
What KIND of seismic waves?
Seismic waves TRAVELING MOST RAPIDLY THROUGH COLD, DENSE REGIONS.
However, COMMA + traveling is also an ADVERB modifying the preceding action -- ricochet -- since the act of TRAVELING happens as a direct result of this action.
For this reason, COMMA + traveling can be said to describe HOW seismic waves RICOCHET.
Thank you so much! Your explanation is crystal clear!

akara2500 Newbie | Next Rank: 10 Posts
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Sat Apr 22, 2017 7:36 am
GMATGuruNY wrote:
Needgmat wrote:
Can you please explain that in OA HOW and WHAT COMMA+VERBing(TRAVELLING) refers to?
Generally, COMMA + VERBing serves to refer to the agent of the NEAREST PRECEDING ACTION.
OA: waves that...ricochet around its interior, traveling most rapidly through cold, dense regions.
Here, the action that most closely precedes COMMA + traveling is ricochet.
Thus, traveling serves to refers to waves, the agent of this action.
Conveyed meaning:
As waves RICOCHET, they are at the same time TRAVELING.

Quote:
2) Can you please explain more about that and which clause can't be connected by conjunction and and hence can't be VALID parallel structure.
Parallel forms must serve the SAME FUNCTION.
A that-modifier is an ESSENTIAL MODIFIER: one that is necessary to convey the intended meaning of the sentence.
A which-modifier is a NONESSENTIAL MODIFIER: one that can be removed without altering the basic meaning of the sentence.
Since a that-modifier and a which-modifier serve different functions, they cannot be connected by a conjunction such as and.
Hi Mitch
Then how about Noun + Comma + Modifier + Comma + clause, this modifier between these 2 commas is also nonessential?

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