Only one of the three colors of black, red and white is selected to take the ball, so it is three choices 1, C3 1=3.

2. Press 3: 1: 0.

Choose a color from black, red, white, C3 1, and then choose C2 1 from the remaining two colors, that is, C3 1C2 1, which can also be written as A33, A33=6.

3, press 2: 2: 0 to get it

In black, red and white, just choose the color that does not take the ball, take two balls for the other two colors, and choose 1 of the three colors, that is, C3 1=3.

4. Just press 2: 1: 1.

That is, as long as the colors of two balls are selected, one ball is selected for the remaining two colors, and 1, C3 1=3 is selected among the three colors.