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by vishugogo » Tue May 13, 2014 3:34 am
Not able to understand the verb issue in option D and E[/img]
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by ilyana » Tue May 13, 2014 4:01 am
vishugogo wrote:Not able to understand the verb issue in option D and E[/img]
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
--- correct

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
--- misplaced modifier ("over the past twenty years" seems to modify "development")
--- sentence structure: AND should connect parallel elements; here the second element is the verb "are drawing", but there is no verb in the first part of the sentence


C) Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
--- misplaced modifier ("over the past twenty years" seems to modify "development")
--- sentence structure: AND should connect parallel elements; here the second element is the verb "are drawing", but there is no verb in the first part of the sentence



D) 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]

--- Present Participle ("drawing") implies SIMULTANEOUS action with the main verb. The main verb ("have amassed") is in Present Perfect and denotes an action in the past with the result in the present. The adverb "NOW" gets in the way of this structure.

E) Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood, [now drawing solid conclusions]

--- Present Participle ("drawing") implies SIMULTANEOUS action with the main verb. The main verb ("have amassed") is in Present Perfect and denotes an action in the past with the result in the present. The adverb "NOW" gets in the way of this structure.
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by aditya8062 » Tue May 13, 2014 5:55 am
ilyana
i eliminated D and E on the basis that the main intent of the sentence was the fact that "Neuroscientists are now drawing solid conclusions" and hence this fact should be place as a main clause rather then placing it as a modifier,which is being done by D and E .

ilyana dont u think present perfect tense indicates something that happened in the past and is still on going !! so why "now" cannot go in hand with this !

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by ilyana » Tue May 13, 2014 10:49 am
ilyana dont u think present perfect tense indicates something that happened in the past and is still on going !!
This is one of possible meanings of Present Perfect, but not the only one.
In the sentence below I'm using FOR/SINCE + Present Perfect, and such sentences are likely to be interpreted the way you suggested:
I have lived in my own house for 3 years. --- I'm still living there.
George has worked in publishing since 2000. --- he is still working in publishing.

However, without FOR/SINCE, sentences tend to indicate a state or action COMPLETED in the past but important to the present:
I have been to China. --- I'm not in China now, but the fact that I was there is somehow relevant to the present.
George has lost his keys. --- he is not losing them now, but there are consequences to the fact that he lost his keys (he doesn't have them now).

https://www.manhattangmat.com/forums/sc- ... 381098862f
Read this thread through. I know it is a long one, but I like Ron's explanations there very much! It gave me a deeper understanding of Present Perfect usage.
i eliminated D and E on the basis that the main intent of the sentence was the fact that "Neuroscientists are now drawing solid conclusions" and hence this fact should be place as a main clause rather then placing it as a modifier,which is being done by D and E .
If you have a well-developed sense for language and intended meaning, you can (and should) use these skills to your advantage on the GMAT.
My approach is to rely on more technical things if possible.
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by aditya8062 » Wed May 14, 2014 11:25 am
ilyana, the comma + verbing modifier can either present result of the previous clause or provide an elaboration of the previous clause

now do u really feel that in D or E either of these stuff is accomplished? .honestly i don't think so and here is my logic .you never amass a knowledge and then draw conclusions !! in fact you always make hypothesis and then draw conclusion and in a process u might amass lot of knowledge

all i am contending is that somehow i feel that in D and E the sequencing of process is little reversed and hence comma + verb ing modifier is little awkward

by this logic i feel that had D been as below would still be wrong
modified D: Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, drawing solid conclusions about the human brain grows and how babies acquire language

what is your opinion on this ?
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by e-GMAT » Wed May 14, 2014 10:51 pm
Before we get to the problem in options D and E, let's look at the intended meaning of choice A. Remember we need to first thoroughly understand the original sentence so that we can properly gauge the other answer choices.

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.

This sentence indicates the following:
"¢ Over the past 20 years, neuroscientists have collected a lot of knowledge about 2 things - brain and its development
"¢ Neuroscientists are now drawing conclusions about 2 things - growth of human brain and acquiring language.
Key things to notice:

Two actions are being discussed:
a. In the past, scientists collected information
b. Now in the present context, scientists are drawing conclusions

Now let's take a look at choice D:

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.

Let's focus on the sequencing of tenses in this sentence. For this, I will omit "now" for now. We will bring this back after this bit of discussion.

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

Let's read this sentence now and see what meaning it communicates.
"¢ Over the past 20 years, neuroscientists have collected a lot of knowledge about 2 things.
"¢ The verb-ing modifier can either present result of preceding clause or elaborate on the preceding clause. Let's see which meaning is logical here:
o Elaborating - They collected a lot of knowledge in the past by drawing solid conclusions about 2 things.
 This seems illogical since one does not collect information by drawing conclusions.
o Result - They collected a lot of knowledge in the past and this led to them drawing solid conclusions.
 This seems rather logical. After they collected knowledge, they were able to draw solid conclusions.

But notice one very important thing. In this sentence, both the actions appear to have taken place in the past. The information was collected in the past and the conclusions were also drawn in the past.

Now bring back your understanding of choice A. Per choice A, collection took place in the past but the conclusions were being drawn in the present.

So this is the first reason for rejecting choice D - the shift in the meaning of the sentence.

Now let's bring back the word "now". This word interferes with the logical sequence of actions established in choice D. The logical sequence as we determined was that both actions took place in the past, but the presence of "now" forces the second action to take place in present, thereby creating a conflict.

And lastly, as aditya8062 has pointed out, there is a focus shift in choice D.

Note that modifiers typically do not present the main point of the sentence: they only give additional information. In the original sentence, the subject of the main clause is "Neuroscientists" and the verb is "are drawing". So, the intended focus is to say that neuroscientists are now drawing solid conclusions about something. This focus is now shifted to the collection of information.

Concluding Comments:
It's very important to understand the meaning of the original sentence so that you can assess answer choices in the appropriate light. Remember, grammar is a tool to help you communicate ideas. But there is no use of learning about grammar rules if you do not pay attention to what it is that you have to communicate using these tools.

Regards,
Meghna