Somestudentsgetsonervousbeforeanexamthattheydopoorlyeveniftheyknowthematerial．SianBeilock，apsychologyprofessorattheUniversityofChicago，hasstudiedthesehighlyanxiousexam-takers．"Theystartworryingaboutther

　　Some students get so nervous before an exam that they do poorly even if they know the material．Sian Beilock，a psychology professor at the University of Chicago，has studied these highly anxious exam-takers．

　　"They start worrying about the results．They might even start worrying about whether this exam is going to prevent them from getting into the college they want．And when we worry，it actually uses up attention and memory resources that you could otherwise be using to focus on the exam，"says Sian Beilock．

　　The researchers tested the idea on a group of 20anxious college students．They gave them two short math exams．After the first one，they asked the students to either sit quietly or write about their feelings about the coming second exam．

　　The researchers added to the pressure．They told the students that those who did well on the second exam would get money．They also told them that their performance would affect other students as part of a team effort．

　　Professor Beilock says those who sat quietly scored an average of 20% worse on the second exam．But the students who had written about their fears improved their performance by an average of 5%．

　　Next，the researchers used younger students in a biology class．They told them before final exams either to write about their feelings or to think about things unrelated to the exam．

　　Professor Beilock says highly anxious students who wrote about their feelings got an average grade of B+，compared with a B-for those who did not．

　　But what can they do if students do not have a chance to write about their fears immediately before an exam or presentation？Professor Beilock says students can tryit themselves at home or in the library and they can still improve their performance．

　　61．In which paragraph does the author introduce the background（背景） of his study？___

　　A．In the first paragraph．

　　B．In the second paragraph．

　　C．In the third par