Hi San,
Like all aspects of our CATs, our Reading Comprehensive passages are constantly reviewed to ensure that they reflect both the content and the difficulty level of the actual GMAT. If our passages seem difficult, there are a few explanations. First, are you taking notes based on context cues in the passage? Using keywords and organization to summarize the author's main idea can make a given passage much easier. Second, are you spending more time focusing your studies on CR and SC than on reading? The entire verbal section is adaptive, so if you are struggling with Reading Comprehension in particular, it may indicate that your accuracy on the other two verbal question types is pulling the overall difficulty of the verbal section up to a level where the passages are a challenge.
Let me know if you have any other questions!