第21题: [单项选择]Questions 19 to 22 are based on the passage you have just heard. A. Cave building technique. B. Language and art. C. Ice Age dancing. D. Heating system. 参考答案:B 答案解析:[听力原文] What did the people in the Ice Age invent
第22题: [单项选择]确定某因素与某病联系强度最好用()。 A. 总人群中该病人发病率 B. 患病率 C. 相对危险度 D. 暴露于某因素的频率 E. 总人群中该病的发病率与死亡率之比 参考答案:C