<p>Probably you just need more practice with CR, since it seems random, but it's most likely due to the fact that you understand certain passages better than others. Some people suck at art/poetry passages, but rock at narratives or something..</p>
<p>How many of the questions you're getting wrong are Sentence Completion, how many are Short Passage questions, how many are Long Passage Questions that are fiction, and how many are Long Passage questions that are nonfiction?</p>
<p>Agreed with Gothfather and shiomi. perhaps you're just an inconsistent reader, try to read everything you can and ENJOY it. However, if its the sentence completions thats causing this variance, then its normal-> just look up the words and expand your vocab.</p>