First, let me quote the GMAC representative Rebecca
"Your difficulty level depends on your ability to answer questions of the same question type. So your performance on Sentence Correction will not affect the questions you receive for Reading Comprehension or Critical Reasoning. Or any questions you encounter in the Quant section, for that matter. Thanks for asking!
Rebecca"
The link to the discussion is here.
https://www.beatthegmat.com/how-does-the ... 14296.html
So unless GMAC is deliberately lying to us...this means that RC difficulty is not influenced by how you do on CR and SC. You should also know that RC does not adapt within the passage. So that makes RC the LEAST adaptive portion of the GMAT BY FAR!
There are only two or three chances for the GMAT to adapt on Reading Comp. The actual first passage will be likely be a middle level passage but the pre-selected questions might be of different levels of difficulty to try to see what you can do.
The second passage will be selected based on how you handled the first passage. The passage itself may be more or less difficult than the first and each question will have its own level of difficulty.
The third passage is then based on how you have done on the other two and then the fourth passage (if you get one) is based on all three. Add to this the fact that you might have one entire passage that is an "unscored item." It all adds up to not too many chances to prove yourself of RC.
The point is that the first passage has not adapted to you and the second passage is based only on what you did with the first. You cannot afford to bomb out on the first passage!! This is not like any other question type. You may be facing 4 or 5 questions (even 6) so make sure you give that passage your best and realize that although you might miss a tough question here and there you cannot afford to have an entire passage slip away from you.
Hope that helps!