市场定位战略包括（）。 ["A．产品差别化战略","B．人员差别化战略","C．服务差别化战略","D．形象差别化战略","E．价格差别化战略"]
登革热的潜伏期为 ["A．3～15天","B．15～30天","C．1～2天","D．15～45天","E．2～7天"]
登革热的主要流行季节为 ["A．秋季","B．春季","C．夏秋雨季","D．冬春季","E．秋冬季"]
信息传输问题
3周前刚注射过丙种球蛋白的儿童要注射麻疹疫苗应推迟 ["A．4周","B．2周","C．3个月","D．6个月","E．2个月"]
信息的不可否认性
