Two teenagers doing tricks on skateboards.
Teens are riding skateboards.
YOU ARE RIDING A SKATEBOARD WHILE DOING TRICKS.
exists e1 x1 x2 x3 x4.(a_topic(x1) & on(e1,x4) & n_skateboard(x4) & Theme(e1,x3) & Actor(e1,x2) & v_do(e1) & n_trick(x3) & (x1 = x2) & n_teenager(x1) & card_eq_2(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_skateboard(x2) & n_teens(x1))