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

【申友解析】

正确答案：A

本题的主语是Neuroscientists，既解释了过去的工作，也说明了现在的成就。中间部分作为插入语解释说明了过去20年间的Neuroscientists 的工作。时态为一般过去时，且分词短语作状语，修饰主语。
A 正确
B and are造成整个句子失去了谓语动词
C amassing作为形容词，造成句子失去了谓语
D drawing修饰主句主语，但是时态不正确，使用现在完成时，造成语义中心的转移
E 同上