Skateboarder grinds a concrete railing.
The skateboard is black
No way to know the color the skateboarder's skateboard is black. It could be red or even purple.
exists e1 s1 x1 x2.(ne_nam_skateboarder(x1) & Theme(e1,x2) & Actor(e1,x1) & v_grind(e1) & n_railing(x2) & a_concrete(s1) & Theme(s1,x2))
exists s1 x1.(n_skateboard(x1) & Theme(s1,x1) & a_black(s1))