Monopoly maximizes its profit mainly rely on its ___. A: demand curve B: cost curve C: supply curve D: demand curve and cost curve

 AS曲线，AD曲线（AS curve，AD curve）

The tracks of high-speed train must have a ________ A: longer curve radius B: shorter curve radius C: thinner curve radius D: wider curve radius

An increase in labor productivity shifts the A: labor demand curve rightward. B: labor demand curve leftward. C: labor supply curve rightward. D: labor supply curve leftward

If the Engel curve slopes up, then the demand curve slopes down.

The best no-trade point for a country on an increasing cost production possibilities curve is where: ( ) A: the curve touches the vertical axis. B: the curve touches the horizontal axis. C: the origin. D: the curve touches the highest indifference curve.

在MAYA中绘制一条曲线之后，需要重新调整曲线上点的分布，可以使用（)。 A: A.Rebuild Curve B: B.Smooth Curve C: C.Modify Curve D: D.Attach Curve

The absorption curve is ( ). A: The curve of the relationship between the concentration of light-absorbing substance and absorbance. B: The curve of the relationship between the concentration of light-absorbing substance and transmittance. C: The curve of the relationship between the wavelength of incident light and the thickness of light-absorbing substance solution. D: The curve of the relationship between the wavelength of incident light and the absorbance of a light-absorbing substance.

What is the main difference between probability density function (PDF) and histogram? A: The calculation methods for histogram and PDF are different B: The values on histogram curve are larger than the values on PDF curve C: The shapes of histogram curve and PDF curve are different D: The integration of the PDF curve equals 1, the step of ordinate axis in the histogram is 1

vertical curve