求教OG12-21Neuroscientists, having amassed~

nami123

OG12-21Neuroscientists, 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

请教OG-D解释，有关时态的错误怎么理解？
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.

如果没有逻辑意思（或者句子重心改变）的错误，DE错误如何理解？求教NN~

nami123

enkyklios 发表于 2013-4-22 19:13
我认为应该是；usually some sort of transition or difference is indicated between the past and the p ...

谢谢enkyklios！
把RON的解释share给你和大家：
the "comma + ing" modifier should only be used when:

(A)
it MODIFIES THE ENTIRE ACTION of the preceding clause, and it APPLIES TO THE SUBJECT of that clause;

AND

(B)
one of the following is true:
(1) the "ing" action is SIMULTANEOUS with, and SUBORDINATE
to, the main action;
- i ran down the sidewalk, flapping my arms wildly
(2) the "ing" action is a DIRECT AND IMMEDIATE CONSEQUENCE of the main action.
- i got a 100 on the most recent exam, bringing my average up to 91

这道题，drawing表示与amass同时发生，amass是已经完成的动作，但是这里又用了now，所以OG说does not fit
open to discussion~;)

nami123

           OA-A

enkyklios

对D有疑问还情有可原，E的话根本就算不上个句子。

D：  ，now drawing solid conclusions about how the human brain grows and how babies acquire language.   显然不是 non- modifier.     ( 得出……结论)    很容易误以为它是结果状语。但是不能这样用。

nami123

enkyklios 发表于 2013-4-22 17:55
对D有疑问还情有可原，E的话根本就算不上个句子。

D：  ，now drawing solid conclusions about how the h ...

,now drawing ...在这里做结果状语是不对的，这个我理解，因为drawing并不是have amassed这个动作的直接结果（根据逻辑意思）
OG的后半部分解释---seems to modify adulthood.是不对的，如果要修饰adulthood，不加逗号更合适。
但是前半部分有关时态的解释，完全不懂，请NN指教！

enkyklios

我记得以前有人问过完成时可不可以后边跟分词作状语，应该是这个意思吧。

nami123

enkyklios 发表于 2013-4-22 18:07
我记得以前有人问过完成时可不可以后边跟分词作状语，应该是这个意思吧。  ...

恩恩，就是这个考点 ~~~可是我不理解为什么啊 ..
google了一下，看到instructor的解释是：
when you use the word “now”, there is usually some sort of transition or difference indicated between the past and the present. in a sentence that is meant to highlight that sort of difference, it's extremely unlikely that you're going to be able to convey an action that is simultaneous with, or is a direct and inevitable result of, the first action -- that would seem to be self-contradictory. therefore, i think it's unlikely that you're going to see "comma + now + VERBing" a as a legitimate modifier.
仍然不理解 ... 求助求助 T T

enkyklios

这不是官方回答吧，怎么感觉回答的怪怪的

enkyklios

什么叫  there is usually some sort of transition or difference indicated between the past and the present.
而且逗号连接一大堆句子。

enkyklios

我认为应该是；usually some sort of transition or difference is indicated between the past and the present. 或者；there is usually indicated some sort of transition or difference between the past and the present.