a boy does a gymnastic trick under a tree.
A girl does a somersault under a tree.
There can be either a boy or a girl.
exists e1 s1 x1 x2 x3.(under(e1,x3) & n_tree(x3) & Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & n_trick(x2) & a_gymnastic(s1) & Theme(s1,x2) & n_boy(x1))
exists e1 x1 x2 x3.(under(e1,x3) & n_tree(x3) & Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & n_somersault(x2) & n_girl(x1))