Because of an impared ability to focus and a tendency to become easily distracted, individuals with attention-deficit hyperactivity disorder may have an especially difficult time dealing with what barrier to effective listening

Before they can be published, scientific papers must be peer-reviewed. this means that: a) some other scientific experts read the papers and guarantee that they are true. b) some other scientific experts read the papers and provide quality control by eliminating many mistakes. c) an editor reads the papers, to make sure that all the semicolons are in the correct places. d) everyone in the world is given the opportunity to comment on the papers through a specially maintainedblog. e) government bureaucrats read the papers, to be sure that the papers do not insult the political positions ofthe current officeholders.