Hi Abdulla,
Nothing magical, not really a trick or anything, but I find that when I space out during verbal (which I find is much more likely to happen than on math), what helps is to pause every so often and paraphrase what I just read in my head. It may seem like it takes extra time, but in the end it's less time than if you zone out and have to re-read an entire passage for example.
So after every paragraph, you might take 1-2 seconds to remind yourself what that paragraph was about, keep yourself focused. Some people jot down notes on the whiteboard for the same purpose, which can be helpful.
Finally, in reading comp, it's good to focus on opinions in the passages, and certain keywords that emphasize a contrast or emphasis ("however", "therefore", etc). Those can act like road signs to wake you up a bit and let you know that this is an important statement, and more likely to have a question on it.
Jen Kedrowski
Kaplan Test Prep & Admissions
GMAT Teacher
MBA Admissions Consultant
National Product Team Member