Dear Ron
I have two questions about Comma, ing modifier. I know if "comma, ing" appears at then end of a clause, it modifies the clause. But in many times, i found that it is inserted in the middle of a sentence such as: 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 OA of GMAT prep).
in this sentence, does "comma, having amassed a wealth of knowledge... adulthood" as a adjective modify neuroscientists or as a adverb modify the later action-are drawing? and if it act as a adverb to modify the later action" are drawing", how does it modify? is there any connection between these two things?
And also, in some cases, which action does "comma, ing" in the middle of a sentence modify when there are several actions before it, including the verb and also one or more particles.
Thanks in advance, I have long struggled in this kind of usage of "comma, ing" in the middle of a sentence.