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题库 / OG13-SC-25
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.
Neuroscientists, having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood, are
Neuroscientists, having amassed a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
Neuroscientists amassing a wealth of knowledge about the brain and its development from birth to adulthood over the past twenty years, and are
Neuroscientists have amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood,
Neuroscientists have amassed, over the past twenty years, a wealth of knowledge about the brain and its development from birth to adulthood,
题目分析：
本题的原句有点长，其实主干很简单，去掉长长的插入语having amassed a wealth of knowledge over the past twenty years about the brain and its development from birth to adulthood，主干为：
Neuroscientists are now drawing solid conclusions about how the human brain grows.
选项分析：
A选项：Correct. 本选项在语法和逻辑上均是正确的。
B选项：and是连词，需要连接两个句子。但在本选项中，and身前的句子没有谓语动词。
C选项：and身前的句子没有谓语动词错误同(B)。
D选项：划线部分身后的now drawing是伴随状语，本选项在语法上是没有错误的。但是，依据图形背景原则，相对于“下结论”来说，“积攒知识”的持续时间必然更长，其是“下结论”这个事件的背景。因此，draw应为主句，amass应为从句（伴随状语）。
E选项：本选项错误同(D)。
ing不能随意乱用
需有因果关系
Neuroscientists are now drawing solid conclusions about how the human brain grows.
D选项：划线部分身后的now drawing是伴随状语，本选项在语法上是没有错误的。但是，依据【图形背景原则】，相对于“下结论”来说，“积攒知识”的持续时间必然更长，其是“下结论”这个事件的背景。因此，draw应为主句，amass应为从句（伴随状语）。
举个简单的例子。
我们会说
The bike is near the house.
但很少说
the house is near the bike.
在这个句子中，我们用near分离了自行车和房子。这就被称为图形背景分离。其次，因为house是更大的、静止的事物，更容易作为参考，而bike更小，我们就把bike当做图形，而把house当做背景。
GMAT考试通常用主从句来考查考生对于图形背景理论的理解。顾名思义，语言使用者肯定要将主句作为“图形”来凸显，用从句来交代“背景”情况。依上述描述可知，图形更小，背景更大。那么，两个句子怎样比较大小呢？其实很简单，由于句子讲的一般都是一个事件，而事件最重要的是时间属性，所以，在【时间轴上持续时间长】的事件必然是更大的事件，即，背景事件；在【时间轴上持续时间短】的事件必然是更小的事件，即，图形事件。
因此，从句（或者分词短语等非谓语动词引导的短语）需要在时间上延续的更长，主句需要在时间上延续的更短。例如：
(1) Studying Chinese, people felt hard.
(2) **Feeling hard, people studied Chinese.
句(1)是正确的，这是因为，我们肯定是在学习中文的过程中感觉到困难的，所以“学习中文”这件事显然延续的时间更长，应作为背景（从句）；“感觉困难”延续的时间相对更短，应作为图形（主句）。句(2)是错误的。
还有，句子本意是强调现在做了些什么，这应该是主句
1) it should apply most nearly to the subject of the preceding clause (as you've said); and, even more importantly,
2) it should have one of the following RELATIONSHIPS to that clause:
* immediate consequence
* simultaneous, but lower-priority, action
here, this modifier doesn't have either of these 2 relationships to the main clause, so it's used inappropriately.
when we say "immediate consequence, we mean a consequence that is proximate, immediate, and produced as an essentially unavoidable result of the main action. for instance:
the bullet entered Smith's brain, killing him instantly --> this is an immediate and automatic consequence; if the bullet does this, then smith will be killed.
John scored 90 on the most recent test, raising his overall average by two points --> again, an immediate and automatic consequence; if john gets this score, there will automatically be the stated consequence for his average.
in the problem at hand, drawing new conclusions is not an automatic and essentially unavoidable consequence of amassing the knowledge in question; the researchers must actively go beyond just amassing the knowledge to draw those conclusions.
1) it should apply most nearly to the subject of the preceding clause (as you've said); and, even more importantly,
2) it should have one of the following RELATIONSHIPS to that clause:
* immediate consequence
* simultaneous, but lower-priority, action
here, this modifier doesn't have either of these 2 relationships to the main clause, so it's used inappropriately.
when we say "immediate consequence, we mean a consequence that is proximate, immediate, and produced as an essentially unavoidable result of the main action. for instance:
the bullet entered Smith's brain, killing him instantly --> this is an immediate and automatic consequence; if the bullet does this, then smith will be killed.
John scored 90 on the most recent test, raising his overall average by two points --> again, an immediate and automatic consequence; if john gets this score, there will automatically be the stated consequence for his average.
in the problem at hand, drawing new conclusions is not an automatic and essentially unavoidable consequence of amassing the knowledge in question; the researchers must actively go beyond just amassing the knowledge to draw those conclusions.
介词短语修饰的位置、句子完整
A over the past twenty years修饰了knowledge，变成定语;应当修饰动作更为合理——但这里似乎可以接收
B句子不完整，Neuroscientists缺谓语；且over the past 20 years 变为修饰development，改变句子意思
C 同B，缺谓语；且over the past 20 years 变为修饰development，改变句子意思
D把主干变为修饰；drawing可能被误读成修饰adulthood
E 同D
DE 用ING做伴随状语错误
ING修饰语的两个作用：
1 与主句动作同时发生 当被修饰主句已经是完成时态，那么后面的现在分词本身就不可能再与主句动作发生在同一时刻，只可能行使伴随结果的功能
2 主句动作的即时结果 immediate consequence 收集了20年证据并不是得出结论的必然结果
所以DE都不对"
②and要判断两个分句是不是结构完整。B,C的结构不完整
③V-ing可以作状语也可以作定语，所以有歧义的可能。D,E处可能在修饰adulthood。此外，作为伴随状语，传达的是结果的意思，但是amass knowledge和drawing conclusions没有这样的必然结果的逻辑关系，D，E错误。
D选项：划线部分身后的now drawing是伴随状语，本选项在语法上是没有错误的。但是，依据图形背景原则，相对于“下结论”来说，“积攒知识”的持续时间必然更长，其是“下结论”这个事件的背景。因此，draw应为主句，amass应为从句（伴随状语）。
所以A正确
A中的having amassed，因为有逻辑主语，所以既可以看成是伴随状语也可以看成是插入语，都是在修饰 Neuroscientists are drawing conclusion这个句子。伴随着积累知识，他们形成了结论。
D/E，按图形背景原理形成结论发生时间短于经过20年的积累知识，前者做主句更优。
现在分词做伴随状语起到伴随的动作和伴随的结果两种功能，如A就是伴随着积累知识的动作，形成了结论；E是他们积累知识，伴随的结果是形成了结论。
伴随的动作表示与主句动作同时发生，having则表示先时性；伴随的结果需要是主句动作的直接的、自然而然的结果。E积累知识并不会自然而然就形成结论，drawing conclusion用法不好。