The boy is coming down the amusement slide on his knees.
The boy is on the swing.
You can't be both on the swing and on the amusement slide, you can only be at one place at a time.
exists e1 x1 x2 x3 x4.(n_knee(x4) & of(x4,x2) & n_male(x2) & n_slide(x2) & of(x2,x3) & n_amusement(x3) & n_boy(x1) & down(e1,x2) & on(x2,x4) & Actor(e1,x1) & v_come(e1))
exists p1 x1 x2.(n_swing(x2) & n_boy(x1) & on(x1,x2))