A skateboarder slides down a stair rail in the dark.
A skateboarder does a trick.
Sliding down a stair rail does not necessarily mean one is doing a trick.
exists e1 s1 x1 x2 x3 x4.(n_dark(x4) & in(e1,x4) & a_down(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_slide(e1) & n_rail(x2) & of(x2,x3) & n_stair(x3) & n_skateboarder(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & n_trick(x2) & n_skateboarder(x1))