A skateboarder shows off his skills.
A skateboarder sits on the curb
Skateboarder cannot show off his skills while sitting on the curb.
exists e1 s1 x1 x2.(a_off(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_show(e1) & n_skill(x2) & of(x2,x1) & n_male(x1) & n_skateboarder(x1))
exists e1 x1 x2.(n_curb(x2) & on(e1,x2) & Actor(e1,x1) & v_sit(e1) & n_skateboarder(x1))