The ground is covered in snow.
The ground is visible.
COVERED IS NOT VISIBLE
exists e1 x1 x2.(n_ground(x1) & in(e1,x2) & n_snow(x2) & Theme(e1,x1) & v_cover(e1))
exists s1 x1.(n_ground(x1) & Theme(s1,x1) & a_visible(s1))