Two kids in a green tree.
There are children in their backyard playing in a tree.
The tree may belong to someone else and not be their tree.  The tree may not be in a backyard.  The children may be in a activity other than playing.
exists s1 x1 x2.(a_topic(x1) & in(x1,x2) & n_tree(x2) & a_green(s1) & Theme(s1,x2) & n_kid(x1) & card_eq_2(x1))
exists p1 s1 x1 x2 x4.(in(p1,x2) & n_tree(x2) & exists x3.((x1 = x3) & in(x3,x4) & n_child(x3)) & n_playing(x4) & a_backyard(s1) & Theme(s1,x4) & of(x4,x2) & n_thing(x2))