Passage Two
[29]Do you have a tough math test coming up? Then listen to some classical piano music just before the test. You might end up with a higher score.Researchers at a university in California conducted an experiment. They asked a group of college students to listen to some piano music by a famous 18th century composer before taking a math test. They were surprised to find that the students' scores jumped 8 to 9 points. [30]The music seems to excite nerve activities in the brain similar to the activity that occurs when a person is figuring out a math problem. However, the scientists warn that before you get too excited about applying this method to your math test, [31]you should remember that brain-exciting effects last only 10 to 15 minutes. Would rock music work as well as the piano music did? No, the scientists say. In fact, the less complex music might even interfere with the brain's reasoning ability.

Questions 29 to 31 are based on the passage you have just heard.
29. What is this passage mainly about?
正确答案：D
解析：题目询问文章的主旨是什么。关键是要听到文章开头的三句话，由此可知D正确。主旨类题考查考生对短文的主题或主旨大意的概括理解，一般出现在短文的第一题或者最后一题。
30. Why can classical music play a positive role in problem solving?
正确答案：C
解析：题目询问为什么古典音乐能够在解决问题的过程中起到积极作用。关键是要听到“（古典）音乐似乎刺激大脑里的神经活动”。故选C。符合短文听力“听到什么选什么”的原则。
31. What is one of the findings of the research?
正确答案：A
解析：题目询问研究的发现之一是什么。关键是要听到“你应该记住，刺激大脑的效果只能持续10-15分钟。”故A正确而D错误。B中的Piano music应改成The less complex music，C未提及。