第29题: [单项选择]与以医院为基础的病例对照研究相比,队列研究的主要优点是() A. 易于研究发病很低的疾病 B. 能够探索有无因果联系 C. 易于获得非暴露组的观察对象 D. 可直接估计所研究疾病的发生率 E. 省钱、省时 参考答案:D
第30题: [单项选择]Questions 14-17 are based on the following dialogue.What bothers Nancy about her new neighbors’ son A. He sings in the mid-night. B. He drives too fast. C. His radio wakes her children. D. He comes back too late. 参考答案:C