OG12-SC-21，谁能告诉我这个见鬼的OG解释是怎么回事？

langrenly

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,

答案是A，选得没错，但我觉得D和E选项的问题都是没搞清楚amass和draw两个动作的主次，看了看论坛大多数人也这么认为，但OG的解释是
D选项：“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选项：“Like D, this sentence attempts to attach a present-tense descriptor to a present-perfect clause.”
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请高人指点一下，为啥"now drawing conclusions..."就不fit the opening clause了？而且doing不是修饰主句的主语么？怎么会seems to modify adulthood那？非常疑惑。
顺便再问一下，从整个OG的风格来看，就不大喜欢having这种形式（比如说sc-10，明确的说了having是awkard），这道题的A正确是不是因为相对好一些？

simplebaby

同样迷惑，顶一下。

现在分词如果做定语，那是对前面的n有限定；要是做状语，要么伴随动作，其逻辑主语同主句主语，要么伴随结果，前面整个句子表原因，无逻辑主语。

从本题句意上看，很明显drawing句是表伴随的，不可能是修饰前面n。是否只是因为这样会产生歧义呢？

keith139

D选项中drawing……，应该是表示伴随或者结果的状语从句，但是由于跟主句的谓语动词没有很好的关联性，即不能表示出伴随或者结果的意思。官方解释认为这个是不明确的修饰。now drawing conclusions … does not fit the opening clause, which is in present-perfect tense (have amassed a wealth …) and seems to modify adulthood.主句的现在完成时态表明这个动作已经完成了，而这个伴随又有明显的时间性提示词语now,所以会造成不知道修饰谁的效果。

我自己参照别人的贴这么猜的，不对的话请高人指点一下

AmyGMAT

这道题我是这么理解的，
首先是明确现在分词做状语的两种用法：
1，表示同时发生，两个动作都是一个主语发出的。
2，表示伴随结果，现在分词的逻辑主语是前面的整个句子，动作不是同时发生的。
放到这道题的D选项
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.
可以看出amass和draw这两个动作都是neuroscientist发出的，那么按照上面的两种用法就应该是属于第一种，但是在第一种用法里，同时又要求两个动作要同时发生，这样D就不符合要求了，因为D的主句是现在完成时，分句是一般现在时，两个不同的时态，动作不可能发生。
这也就是OG所说的 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 …)

其次就是现在分词作状语可以修饰先行词，因此这里就会产生修饰adulthood的歧义，认为是adulthood发出了这个动作。
这就是OG解释的 seems to modify adulthood.

abjure

这道题我是这么理解的，
首先是明确现在分词做状语的两种用法：
1，表示同时发生，两个动作都是一个主语发出的。
2，表示伴随结果，现在分词的逻辑主语是前面的整个句子，动作不是同时发生的。
放到这道题的D选项
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.
可以看出amass和draw这两个动作都是neuroscientist发出的，那么按照上面的两种用法就应该是属于第一种，但是在第一种用法里，同时又要求两个动作要同时发生，这样D就不符合要求了，因为D的主句是现在完成时，分句是一般现在时，两个不同的时态，动作不可能发生。
这也就是OG所说的 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 …)

其次就是现在分词作状语可以修饰先行词，因此这里就会产生修饰adulthood的歧义，认为是adulthood发出了这个动作。
这就是OG解释的 seems to modify adulthood.

-- by 会员 AmyGMAT (2010/5/12 1:16:24)

同意AMY 的解答，感觉解释的比较准确。
附上前人置顶讲解的现在分词伴随状语的反向考点。
http://forum.chasedream.com/GMAT_SC/thread-48928-1-1.html

不过Amy或者其他CDER能否提供一下现在分词做状语修饰先行词的OG里面例句或知识点讲解印证下可否？

AmyGMAT

恩 我曾经发过一个很纠结的帖子，里面都是我对现在分词做状语修饰先行词的问题
呵呵 上面有例题，都是prep和OG上的，你可以看看，如果要是怕被误导，你就别看我纠结的问题了哈

AmyGMAT

http://forum.chasedream.com/GMAT_SC/thread-457413-1-1.html

abjure

终于被我抓到了一个OG 例句 关于 分词ing 就近修饰最近的名词。
分词ING 真的一出就是难题，用的活啊！！！

For members of the seventeenth-century Ashanti nation in Africa, animal-hide shields with wooden frames were essential items of military equipment, protecting warriors against enemy arrows and spears.

原题 OG 12-30
30. For members of the seventeenth-century Ashanti
nation in Africa, animal-hide shields with wooden
frames were essential items of military equipment,
a method to protect warriors against enemy arrows
and spears.
(A) a method to protect
(B) as a method protecting
(C) protecting
(D) as a protection of
(E) to protect

Logical predication; Rhetorical construction
Th e underlined part of the sentence begins a phrase describing items of military equipment. It is
awkward and inaccurate to describe items themselves as a method. Replacing the underlined
phrase with the participle protecting creates a modifying phrase that clearly explains the
purpose of the items of military equipment.

C Correct. In this sentence, protecting properly
introduces a modifying phrase revealing the
purpose of the items.

bensonbao

这道题我是这么理解的，
首先是明确现在分词做状语的两种用法：
1，表示同时发生，两个动作都是一个主语发出的。
2，表示伴随结果，现在分词的逻辑主语是前面的整个句子，动作不是同时发生的。
放到这道题的D选项
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.
可以看出amass和draw这两个动作都是neuroscientist发出的，那么按照上面的两种用法就应该是属于第一种，但是在第一种用法里，同时又要求两个动作要同时发生，这样D就不符合要求了，因为D的主句是现在完成时，分句是一般现在时，两个不同的时态，动作不可能发生。
这也就是OG所说的 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 …)

其次就是现在分词作状语可以修饰先行词，因此这里就会产生修饰adulthood的歧义，认为是adulthood发出了这个动作。
这就是OG解释的 seems to modify adulthood.

-- by 会员 AmyGMAT (2010/5/12 1:16:24)

分析得灰常好

jiaying52

这道题我是这么理解的，
首先是明确现在分词做状语的两种用法：
1，表示同时发生，两个动作都是一个主语发出的。
2，表示伴随结果，现在分词的逻辑主语是前面的整个句子，动作不是同时发生的。
放到这道题的D选项
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.
可以看出amass和draw这两个动作都是neuroscientist发出的，那么按照上面的两种用法就应该是属于第一种，但是在第一种用法里，同时又要求两个动作要同时发生，这样D就不符合要求了，因为D的主句是现在完成时，分句是一般现在时，两个不同的时态，动作不可能发生。
这也就是OG所说的 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 …)

其次就是现在分词作状语可以修饰先行词，因此这里就会产生修饰adulthood的歧义，认为是adulthood发出了这个动作。
这就是OG解释的 seems to modify adulthood.

-- by 会员 AmyGMAT (2010/5/12 1:16:24)

Have amazed和make conclusion不是同时发生的，make conslusion也可以看作是积累很多之后的结果。那为什么不能看作是第二种用法，D选项不就可以了吗？求助！