结构性成本动因越多，越有利于企业进行成本控制，达到降低成本的目的。
参考答案：错
常规注水开发油田的开发主要指标有（）、（）、（）、（）四个方面指标。
---What ________ he say to you just now?
---He told me that he ________ his key in the room.
A．did; leave
B．does; left
C．did; had left
D．do; had left
