Two boys are riding a zipline between trees.
Two boys are skydiving.
The boys are riding a zipline not skydiving.
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & between(x2,x3) & n_tree(x3) & n_zipline(x2) & n_boy(x1) & card_eq_2(x1))
exists e1 x1.(Actor(e1,x1) & v_skydive(e1) & n_boy(x1) & card_eq_2(x1))