You definitely should read the passages, as they often contain stuff that you'll need for answering the questions. However, the passages do often contain some material that is irrelevant when it comes time to answer the questions, so don't get hung up on a passage if you're struggling to understand a certain part, because there's a good chance you won't need to understand that part. You should be able to read through them fairly quickly; make sure you familiarize yourself with the passage contents in case you need to refer back.