药材龙胆的薄壁细胞中含有（）
A.大型草酸钙簇晶
B.草酸钙砂晶
C.草酸钙杆状结晶
D.细小草酸钙针晶
E.草酸钙方晶
参考答案：D
Two mutually exclusive projects have conventional cash flows, but one project has a larger NPV while the other project has a higher IRR. Which of the following least likely explains this conflict（）
A. Reinvestment rate assumption.
B. Size of the projects’ initial investments.
C. Risk of the projects as reflected in the required rate of return.
刨削斜槽工件专用夹具上的止推块是为了防止工件在切削力作用下移动（）
