问题 单项选择题

如果要评价某疫苗预防某病的流行病学效果,应采用哪种研究方法

A.横断面调查

B.临床试验

C.队列研究

D.专题调查

E.现场试验

答案

参考答案:E

问答题

简要概括秦汉王朝、三国两晋南北朝、唐朝、宋元时代、明清时期的时代特征。

                                                                                                                                                             

                                                                                                                                                             

                                                                                                                                                             

                                                                                                                                                             

                                                                                                                                                             

判断题