P.C.C.S (Practical Color ordinate system)的（）色相环。

A．coordinateB．gainC．ordinateD．compromise A: coordinate B: gain C: ordinate D: compromise

A．coordinateB．draftC．ordinateD．compromise A: coordinate B: draft C: ordinate D: compromise

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