A boy in a creek throwing a rock.
A boy fell into the creek
A boy can't be in a creek and falling into the creek at the same time.
exists e1 x1 x2 x3 x4.(a_topic(x1) & in(x1,x2) & Theme(e1,x4) & Actor(e1,x3) & v_throw(e1) & n_rock(x4) & (x2 = x3) & n_creek(x2) & n_boy(x1))
exists e1 x1 x2.(n_creek(x2) & into(e1,x2) & Actor(e1,x1) & v_fall(e1) & n_boy(x1))