If you’re studying for the GRE or GMAT and English is your second (or third) language, you’ll definitely want to get some extra reading in by looking for challenging, high-quality GMAT-like publications.
Here’s a few suggestions free online suggestions!:
– NY Times book review (I really like this article’s description of how to use these articles for practice: http://smartestprep.wordpress.com/2010/08/27/the-new-york-times-exercise-reading-comprehension/)
– Scientific American: http://www.scientificamerican.com/
– The Economist: http://www.economist.com/
– The Spectator: http://www.spectator.co.uk/
– Forbes: http://www.forbes.com/
Keep in mind that the GMAT and GRE RC is not “hard” because of it’s incredibly advanced language. Most of it is readily comprehensible, although it may occasionally use unfamiliar scientific or business terminology. The challenge of RC lies in breaking down the rhetoric of the passage, and grasping not only what the author’s argument is, but HOW he/she makes it. Absolutely seek out tougher study materials, but make sure to apply your RC method to new passages as well!