The black dog in front of the tree has a green toy in its mouth.
A dog is in front of a tree at a park.
Being in front of a tree does not necessarily imply being at a park.
exists e1 s1 s2 x1 x2 x3 x4 x5.(n_mouth(x5) & of(x5,x3) & n_thing(x3) & n_tree(x3) & n_dog(x1) & a_black(s1) & Theme(s1,x1) & Theme(e1,x4) & Actor(e1,x1) & v_have(e1) & in(x4,x5) & n_toy(x4) & a_green(s2) & Theme(s2,x4) & in(x1,x2) & of(x2,x3) & n_front(x2))
exists p1 x1 x2.(at(p1,x2) & n_park(x2) & exists x3 x4.(in(x1,x3) & of(x3,x4) & n_tree(x4) & n_front(x3)) & n_dog(x1))