成本从反映差别的不同可分为（）。
A.差别成本
B.边际成本
C.增量成本
D.沉没成本
参考答案：A, B, C
—These days all China is worried about the plane of MH370.
—Yes. All the world wants to know________________.
A．where did the plane go
B．where did the plane landed
C．if the passengers are alive
D．when can we find the plane
什么叫感染谱？
