A little boy swims underwater.
A child swimming.
A boy is swimming underwater.
exists e1 s1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_swim(e1) & n_underwater(x2) & n_boy(x1) & a_little(s1) & Theme(s1,x1))
exists x1 x2.(a_topic(x1) & n_swimming(x1) & of(x1,x2) & n_child(x2))