please explain in detail about what -ing modifiers modify...

[minshum491]

questions
comma + ing can never modify the word just before it??
ing without comma modifies the word before it but that word should be a noun not a verb ??
are these two principles above universal and never refuted in gmat or are they just there to get skeptical when one stumbles upon them...please dont direct me to some other forums because it is not clear elsewhere...please explain it here...

[RonPurewal]

...and this is why you shouldn't try to remember rules as rules.

Rules are a good starting point"”but only a starting point. As you learn, you should replace them in your mind with a bank of examples that will allow you to make more distinctions.

comma + ing can never modify the word just before it??

If this kind of modifier is placed after just a noun, then it describes the noun. But there still must be a clear relationship to the rest of the sentence.

E.g.,

James, standing seven feet tall, is one of the school's best basketball players.
(correct"”James is 7' tall, and there's a clear relationship to his prowess at basketball)

James, standing seven feet tall, is one of the school's best mathematicians.
(incorrect"”no reasonable relationship between height and math ability)

James, who stands seven feet tall, is one of the school's best mathematicians.
(correct"”"who" just has to describe James, without needing a relationship to the rest of the sentence. However, let's hope there's some context that justifies such a weird sentence.)

[RonPurewal]

ing without comma modifies the word before it but that word should be a noun not a verb ??

Basically correct, although there are exceptions that end with __ing but don't act like __ing words (e.g., "including", "using").

If you want to modify a verb/action, you should use comma + __ing.