可使人群易感性升高的因素除了
A.新生儿增加B.免疫人口免疫力的自然消退C.易感人口的迁入D.隐性感染发生后E.免疫人口的迁出或死亡,使人群易感性升高
参考答案:D
In relation to company law, describe the differences between the various classes of shares. (10 marks)
什么是用接触测量法检验表面粗糙度?