第13题: [单项选择]Passage Two Questions 29 to 31 are based on the passage you have just heard. A. It was rising. B. It was lowering. C. It remained unchanged. D. It was fluctuating. 参考答案:B 答案解析:[听力原文]
What is true about the rate of" heart disease between 1992 and 1994 in the United Stat