A guy is doing a trick on a bike.
Boy on a skateboard
The male cannot be on a bike and a skateboard at the same time.
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & on(x2,x3) & n_bike(x3) & n_trick(x2) & n_guy(x1))
exists s1 x1.(ne_nam_boy(s1) & a_topic(s1) & on(s1,x1) & n_skateboard(x1))