A boy skips a rock in a creek.
The boy is in the tub.
A boy can't skip rocks in a creek and be in the tub at the same time.
exists e1 x1 x2 x3.(in(e1,x3) & n_creek(x3) & Theme(e1,x2) & Actor(e1,x1) & v_skip(e1) & n_rock(x2) & n_boy(x1))
exists p1 x1 x2.(n_tub(x2) & n_boy(x1) & in(x1,x2))