a boy smiles underwater.
The boy is asleep.
You need to be awake to smile and thus could not be smiling while asleep.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_smile(e1) & n_underwater(x2) & n_boy(x1))
exists s1 x1.(n_boy(x1) & Theme(s1,x1) & a_asleep(s1))