Because there is only one watercolor painting and it can only be placed in the middle, there is only one situation that can be ignored.

Considering oil painting and Chinese painting as two whole, there are only two kinds of placement positions to choose from, so the arrangement is P2 2.

Look inside the oil painting, the arrangement is P44;

In Chinese painting, the arrangement is P5 5.

Therefore, the overall display mode is P2 2 times P4 4 times P5 5.