They ask alot of tone questions. That will skew the score a little. However, on my dat there were quite a few tone questions so it is good practice. I would use Top Score or Achiever to get a good idea of what the real reading tests are like. Use CDR to find strategies that you are comfortable with and work for you. Take a look at my blog. It compares the top score and Achiever scores with the real dat. I only took 2 full CDR my scores were in the 17 range. The others I used section by section to find a strategy.