If you need to know it for the TOEFL iBT, it's in this book. "Cracking the TOEFL iBT with CD, 2013 Edition, "includes: - Full-length simulated TOEFL iBT with accompanying audio sections on an MP3 CD - Comprehensive grammar review to help you brush up on your basics - Reviews of core concepts plus practice drills for the Speaking, Listening, Reading, and Writing sections - Tips and time-saving techniques to ace the Reading and Writing sections, including updated strategies that reflect the changes to the Reading section - Detailed answers and explanations for the practice test and all practice drills