a boy smiles underwater.
A boy smiles at his friend while they are at the table.
They would not be at a table while underwater.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_smile(e1) & n_underwater(x2) & n_boy(x1))
exists e1 p1 x1 x2 x3.(n_table(x3) & exists p2.at(x1,x3) & n_thing(x1) & while(e1,p1) & at(e1,x2) & n_friend(x2) & of(x2,x1) & n_male(x1) & Actor(e1,x1) & v_smile(e1) & n_boy(x1))