a boy smiles underwater.
A swimmer smiles while beneath the water.
Beneath the water and underwater refers to same. Boy refers to swimmer, who smiles
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_smile(e1) & n_underwater(x2) & n_boy(x1))
exists e1 x1 x2.(n_water(x2) & beneath(e1,x2) & r_while(e1) & Actor(e1,x1) & v_smile(e1) & n_swimmer(x1))