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Neuroscientists and their knowledge

by rx_11 » Tue Oct 26, 2010 8:39 pm
Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.

(A) Neuroscientists, having amassed a wealth of knowledge over the past twenty years about
the brain and its development from birth to adulthood, are
(B) Neuroscientists, having amassed a wealth of knowledge about the brain and its development
from birth to adulthood over the past twenty years, and are
(C) Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(D) Neuroscientists have amassed a wealth of knowledge over the past twenty years about
the brain and its development from birth to adulthood,
(E) Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood






OA is A

But why D & E are wrong?

The OE says :

D The final descriptor in present tense, now drawing conclusions ... does not fit the opening clause, which is in present-perfect tense (have amassed a wealth ...) and seems to modify adulthood.

E Like D, this sentence attempts to attach a present-tense descriptor to a present-perfect
clause.


What does it mean:"not fit the opening clause"? Should we use "now having drawn"??? Moreover, why the final descriptor seems to modify adulthood? I think participle(drawing) always modify the verb of the main clause.. Why it would seem to modify a noun??
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by pesfunk » Tue Oct 26, 2010 8:58 pm
https://gmatclub.com/forum/neuroscientists-96386.html

I'll still let you know whatz the problem with D and E:

in both D and E, the word "are" is missing at the end of the sentence.

rx_11 wrote:Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.

(A) Neuroscientists, having amassed a wealth of knowledge over the past twenty years about
the brain and its development from birth to adulthood, are
(B) Neuroscientists, having amassed a wealth of knowledge about the brain and its development
from birth to adulthood over the past twenty years, and are
(C) Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(D) Neuroscientists have amassed a wealth of knowledge over the past twenty years about
the brain and its development from birth to adulthood,
(E) Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood






OA is A

But why D & E are wrong?

The OE says :

D The final descriptor in present tense, now drawing conclusions ... does not fit the opening clause, which is in present-perfect tense (have amassed a wealth ...) and seems to modify adulthood.

E Like D, this sentence attempts to attach a present-tense descriptor to a present-perfect
clause.


What does it mean:"not fit the opening clause"? Should we use "now having drawn"??? Moreover, why the final descriptor seems to modify adulthood? I think participle(drawing) always modify the verb of the main clause.. Why it would seem to modify a noun??
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by kashefian » Tue Oct 26, 2010 9:09 pm
In my opinion, E is awkward. It would better to say: Neuroscientists have amassed a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years. Two commas before and after "over the past twenty years" seams to be an unessential modifier but as I said it's awkward.

The transition between first and second part of the paragraph in D and E is wrong. There is no conjunction used to clarify this transition. I mean it's awkward to say: Neuroscientists have amassed .... , now drawing solid conclusions ...

A is the correct answer.
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by Jen@VeritasPrep » Wed Oct 27, 2010 6:42 am
Just a couple of clarifying points on D and E. rx_11, the OEs are pointing out the logical discrepancies in time period between the main verb (which is in the present perfect) and in the participial phrase (which has the simple present indicator "now"). When events logically take place during the same time period, the tenses must also be the same.

By eliminating the word "are," both D and E have participial phrases ("now drawing.....") at the end. Participles are ADJECTIVES, which means they modify nouns. When a participial phrase is set off by a comma at the end of the sentence, it can modify EITHER the noun immediately preceding it OR the subject of the previous clause. It's not clear whether the participial phrases in D and E are modifying neuroscientists or adulthood, so they are ambiguous and incorrect.

Hope that helps!
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by GMATMadeEasy » Wed Oct 27, 2010 10:53 am
@jen : a question
When a participial phrase is set off by a comma at the end of the sentence, it can modify EITHER the noun immediately preceding it OR the subject of the previous clause.
comma + ing modifier should always modify the subject, that is what OG mentions . Could you please confirm.
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by rx_11 » Fri Nov 19, 2010 8:11 am
GMATMadeEasy wrote:@jen : a question
When a participial phrase is set off by a comma at the end of the sentence, it can modify EITHER the noun immediately preceding it OR the subject of the previous clause.
comma + ing modifier should always modify the subject, that is what OG mentions . Could you please confirm.

The same question with GMATMadeEasy.

20 days after I post this problem, I get stucked at this question again.

I think it is not the missing "are" problem and not the participle reference problem, but I think it is the tense of main clause and tense of participle problem. But I don't know what's wrong with the tense.

Can any experts give final explaination why D&E are wrong?
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by shovan85 » Fri Nov 19, 2010 11:33 am
rx_11 wrote:Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are now drawing solid conclusions about how the human brain grows and how babies acquire language.

(A) Neuroscientists, having amassed a wealth of knowledge over the past twenty years about
the brain and its development from birth to adulthood, are
(B) Neuroscientists, having amassed a wealth of knowledge about the brain and its development
from birth to adulthood over the past twenty years, and are
(C) Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
(D) Neuroscientists have amassed a wealth of knowledge over the past twenty years about
the brain and its development from birth to adulthood,
(E) Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood
I feel u know why B and C are wrong and A is correct.

As per D the complete sentence is:

Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, now drawing solid conclusions about how the human brain grows and how babies acquire language.

In the above statement, "Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood" is a correct complete statement which is in present perfect tense.

Modifier rule: Noun + comma + Verb ING the ING forms modifies the just previous Noun.

So, .... adulthood, now drawing.... drawing wrongly modifies adulthood, Its actually the Neuroscientists are drawing.

Can you see now how the bold ARE is required?

Wrong things in D:

1. .... adulthood, now drawing.... Wrong modifier.

2. We do not need the DRAWING as a modifier to Neuroscientists either, because we need a Clause (Subject + Verb), we need an action for the neuroscientists, Without usage of "are" it is just a Phrase (the phrase is also Incorrect here).

Being more clear see the below sentence:

I now drawing solid conclusions about how the human brain.

This is wrong as it is not a proper sentence. Verb is necessarily required.

3. If "ARE" were present in the sentence also it would be wrong as along with Present perfect tense we cannot use Simple present tense.

Try this:
I have gone mad, am now drawing solid conclusions about how the human brain.

What the hell is above sentence? Ridiculously wrong.
Its not only a problem of tense mismatch but also a problem of Subject Verb (in the sense one subject two verbs [have gone, am]).

Hope this helps and try yourself to break down E. It is quite similar to D.

Though I can easily figure out D and E are wrong It is very difficult to explain. I have tried my best to explain, still let me know if you have further doubts. Also I am not sure about the way I have stated is correct or not ;)
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by rx_11 » Fri Nov 19, 2010 9:14 pm
shovan85 wrote:
Modifier rule: Noun + comma + Verb ING the ING forms modifies the just previous Noun.

Hi, shovan85

Thanks very much!

But I do not agree with you at this point.

Noun + comma + Verb ING , the ING forms should modify the previous SENTENSE and the action of it, that is to say, the logical SUBJECT of the "ing form" is the subject of the previous sentense.

There are many posts cited by Stacey/Ron saying this principle. I cite two Ron's post:(I can't find the stacey's post)
https://www.manhattangmat.com/forums/bec ... t7381.html
https://www.manhattangmat.com/forums/pos ... tml#p30766

Moreover, I have an example on Manhattan GMAT SC 4th,

RIGHT------Crime has recently decreased in our neighborhood, leading to a rise in property values

The leading clause modifies the previous sentense, the logical subject of the verb"lead" is the "crime", not the "neighborhood". Thus, I think the verbing forms in choice D/E are correct, and they modify the previous sentense, which the logical subject of "drawing" is the Neuroscientists.

I think you confuse the "Noun + comma + Verb ING "& "Noun + Verb ING" , because it is the later one that modifies the noun that immedietely follows the ing form.

--------------------------------------------

Well, to be honest, I think I find why D&E are wrong after I reply you. Because in the Noun + comma + Verb ING form , the ING forms should modify the previous sentense and the action of it, the verb+ing form in D/E does not make sense because the "drawing" cannot modify the previous WHOLE sentense. It is not the previous action that causes the "drawing" action, but it is the Neuroscientists that cause this action.

In that example: Crime has recently decreased in our neighborhood, leading to a rise in property values

It is the whole action that "Crime has recently decreased " leads to the rise, and the logical subject of "leading" is crime. Thus, I finally find the subtle difference of when we can use participle, and when we can't. The two sentenses are the best example.
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by shovan85 » Fri Nov 19, 2010 11:01 pm
my mistake. sorry for the modifier rule.

But can you please let me know the other two mistakes I have pointed out for D is valid or not
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by rx_11 » Sat Nov 20, 2010 1:42 am
shovan85 wrote:my mistake. sorry for the modifier rule.

But can you please let me know the other two mistakes I have pointed out for D is valid or not

:) OK, let me try,
shovan85 wrote:2. We do not need the DRAWING as a modifier to Neuroscientists either, because we need a Clause (Subject + Verb), we need an action for the neuroscientists, Without usage of "are" it is just a Phrase (the phrase is also Incorrect here).
I agree with you at this point. This is why D/E are wrong, because it is the Neuroscientists that cause the "drawing" action, not the whole previous sentense do. Hense, we should not use participle. (main clause+COMMA+verbing)
shovan85 wrote:3. If "ARE" were present in the sentence also it would be wrong as along with Present perfect tense we cannot use Simple present tense.
I don't think so. I think it is OK and grammertically correct to write several events happening in different time in a sentense. For example, I get one on ManhattanGMAT SC 4TH Page111.

Right: Scientist:" The supercollider IS ready, it DID not cost too much, and it WILL provide new insights into the working of the universe."

This sentense contains three different events happening in three different time. But it is correct.

But if you write them in a "report clause"(I call it "report clause" while using the "reporting verbs" such as announce, believe, etc.) For example, "the scientists ANNOUNCED that the supercollider WAS ready, that it HAD not COST too much, and that it WOULD PROVIDE new insights into the working of the universe," then you should change the verb tense.

Hence, if you add a conjunction word (such as and) and a "are" in D/E, it is correct.

Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood and are now drawing solid conclusions about how the human brain grows and how babies acquire language
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