问题
单项选择题
According to the passage, ______.
A．all people can take beta blockers
B．beta blockers are widely prescribed
C．beta blockers work only on test anxiety
D．beta blockers work only to improve test scores if the test-taker truly knows the material
答案
参考答案：D
解析：[分析] 推断题型。 根据对以上几题的解析，可排除选项A和B。又根据文中These drugs seem to help test-takers who have low scores because of test fright，but not those who do not know the material．(此类药似乎有助于那些由于怯场而导致分数低的考试者，却不能帮助那些不了解考试内容的人。)可推断出D是正确答案。