病例对照研究中,样本大小取决于()
A.第一类错误
B.第二类错误
C.人群中暴露的比例
D.预期相对危险度
E.以上都是
参考答案:E
As long as we persist in spreading scientific knowledge among the masses, all the strange beliefs are ________ to go out of our life.[ ]
A.necessary
B.important
C.difficult
D.bound
B细胞不表达下列哪一种CD分子
A.CD154(CD40L)B.CDl9C.CD40D.CD79a与CD79bE.CD80与CD86