Solution to 7.

7. The world isn't flat, nor is the world a perfect sphere.

The two simple statements are

F = The world is flat.

S = The world is a perfect sphere.

Substituting these back, we get:

not-W, nor S

How do we translate this? Well, clearly what the statement means to say is that both of the simmple statements are false. It is false that the world is flat, and it is false that the world is a perfect sphere. So we can translate 'nor' as 'and not':

not-W and not-S

And we get