Well a hole is a hole even if it is in the shape of a triangle and the dimensions mean that it is 3' wide 3' long and 3' deep so it is a cube but if it is a hole than it has no dirt in it because it has been taken out to make it a hole. That is the only one that got me.
If you are looking for the tricks and you can see what the mistake is that they want you to make it is a lot easier.