单项选择题
A.总成本等于总变动成本B.总成本大于总变动成本C.总成本是否大于总变动成本不确定D.平均变动成本的最低点恰好在总成本曲线的拐点上
A.Have met for several time.B.Classmates.C.Don't know each other before.D.Friends.
A.上清中有少量游离抗体B.上清中有少量游离抗原C.上清中几乎无游离抗原或抗体存在D.出现沉淀物是肉眼不可见的
A.they did not queue for the busB.they were foreignersC.the people were unfriendlyD.there were not any reasons
A.特异性指标B.关键性指标C.辅助性指标D.无效指标