$23 \cdot 23$ As shown in the figure, a cubic wooden block with a side length of 3 meters, has a square hole with a side length of 1 meter drilled through the center of each face, all the way through. The edges of these holes are parallel to the corresponding edges of the cube. What is the total surface area (including the inside) of this object in square meters?
(A) 54 .
(B) 72 .
(C) 76 .
(D) 84 .
(E) 86 .
[Solution] Subtract a small square from the center of each face, so their total area is
$$
6 \cdot 3^{2}-6=48 \text {, }
$$

The middle six small square holes, each with a surface area of 4, so the total surface area inside and out is
$$
48+4 \cdot 6=72 \text {. }
$$

Therefore, the answer is $(B)$.