I would like to play with you, _______ I have to do my homework first.
A:or
B:so
C:and
D:but
在棱长为3厘米的正方体木块的正面的中心上打一个直穿木块的洞,洞口呈边长为1厘米的正方形,挖洞后木块的表面积是多少?