A young man riding and grinding his skateboard against the railing.
A person is at a skate park.
If one is riding and grinding one's skateboard against the railing then one is usually at the skate park.
exists e1 s1 s2 x1 x2 x3 x4 x5.(n_railing(x5) & a_topic(s1) & subset_of(e1,s1) & against(e1,x5) & Theme(e1,x4) & Actor(e1,x3) & v_grind(e1) & n_skateboard(x4) & of(x4,x1) & n_male(x1) & n_thing(x3) & subset_of(x1,s1) & n_riding(x1) & of(x1,x2) & n_man(x2) & a_young(s2) & Theme(s2,x1))
exists p1 x1.(exists x2 x3.(at(x1,x2) & n_park(x2) & of(x2,x3) & n_skate(x3)) & n_person(x1))