I don't think "I am twice your size" is wrong. While it's true that "twice" is an adverb, you can argue that it's modifying the verb "am" rather than the size itself. (I could refer to a "daunting size," for example, but not a "twice size.")

But I wouldn't burn any brain cells on this. Anytime you find yourself diagramming a sentence and asking whether a certain grammatical rule applies, you want to shift your focus -- the rule isn't going to magically clarify itself in the middle of a GMAT exam, and GMAT SC is much more concerned with logic and meaning than the nuances of adverbs. Instead, you want to ask yourself if the meaning is clear and logical. If it is, move on to other issues.

I hope that helps a bit!
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mcelroytutoring - i was wondering if you could perhaps make a video regarding how would you tackle this SC question ?

Your youtube videos are really good.

Thanks !

Flattery will get you everywhere, jabhatta2.

Here is a video that might help.


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A ing modifier after comma should agree with subject. Does this always need to be true? If yes, then is there an exception in this case.
Secondly, what's the difference between increase in and increase of, I couldn't use this distinction to eliminate answers. Please help IanStewart GMATNinja @veritasprepkarishma