求分析,关于现在分词的修饰

晒太阳阳阳阳阳

之前总结了prep08笔记关于现在分词和过去分词的修饰情况：
1.当过去分词在句末时，不管有无逗号，一般都是就近修饰名词；但偶尔也做状语修饰整个句子，如He hurried to the hall, followed by two guards. 修饰情况由逻辑决定；
2.现在分词在句末时，无逗号时作就近修饰的名词的定语；
3.当现在分词在句尾且前有逗号时，修饰邻近句子的主语，做主语的伴随状语或做句子的伴随结果。因此不能用句尾现在分词修饰前面句尾的名词；(在GMAT里，having been done的用法错误，应直接用done)
4.当现在/过去分词在句中且前没有逗号,修饰前面紧邻名词；
5.当现在/过去分词在句中且前后都有逗号，有歧义：1)修饰前面紧邻的名词，2)向后修饰后面句子的主语
里面说现在分词前有逗号时只能修饰前面句子的主语，但是做og18的时候发现有一道题就是错在逗号后的现在分析修饰有歧义，所以很困惑
把题目贴上来：
(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
(D) Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood,
请大家帮忙看看到底是我理解有问题，还是笔记存在疏漏，谢谢了

晒太阳阳阳阳阳

把官方解释贴上来~其实这个题我在时态上没把握好，但对D对修饰的解释还存在一点疑惑
A Correct. The explanatory phrase between the subject and predicate is set off by commas, and the main clause contains
both a subject ( Neuroscientists ) and a corresponding verb ( are now drawing ).

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.

LLEOE

D选项now drawing conclusions做伴随状语在语法上没啥错误，只不过句子的意思变了。这句话的重心是想说这群科学家现在得出来了这样一个结论，而积累了这些知识仅仅是作为背景，而D选项句义的重心则变成了这群学者这么些年积累了很多知识，而得出结论却变成了修饰部分。

晒太阳阳阳阳阳

LLEOE 发表于 2017-11-3 12:38
D选项now drawing conclusions做伴随状语在语法上没啥错误，只不过句子的意思变了。这句话的重心是想说这群 ...

句子重心确实发生了改变，我懂了~
刚刚看Ron的解释发现在这里做伴随状语也是有问题的，首先不能伴随动作同时发生，另外“得出结论”也不能作为“积累知识”的不可避免的伴随结果