4. (3 points) In the grid paper in the figure, there are five small squares numbered $1,2,3,4,5$. By shading two of them, the shaded parts in the figure can exactly form the net of a cube. The numbers of these two squares can be ( )
A. 1,2
B. 2,3
C. 3,4
D. 4,5
【Analysis】According to the 11 characteristics of the cube net, only by shading $4, 5$ or $3, 5$, can it form the "1-3-2" structure of the cube net with the 4 already shaded squares. Therefore, the answer is: D.