The sky appears clear.
The sky is covered in clouds
A sky that is covered in clouds is not clear.
exists e1 p1 x1.(n_sky(x1) & exists s1.(Theme(s1,x1) & a_clear(s1)) & Topic(e1,p1) & Actor(e1,x1) & v_appear(e1))
exists e1 x1 x2.(n_sky(x1) & in(e1,x2) & n_cloud(x2) & Theme(e1,x1) & v_cover(e1))