Look at me: first find out the drawing method of each column, 2 for each grid, and choose 1.

Then the different painting methods are: 2*2*2=8.

There are 9 columns of rectangles in the title, which are colored in different ways first.

The last remaining 1 column, no matter how it is drawn, will be the same as the 1 column drawn before.

The reason is not the first grade of primary school, it's so difficult!