He is skateboarding.
A skateboarder is showing off for his wife.
He is skateboarding does not imply showing of for his wife.
exists e1 x1.(n_male(x1) & Actor(e1,x1) & v_skateboard(e1))
exists e1 s1 x1 x2.(a_off(s1) & Manner(e1,s1) & for(e1,x2) & n_wife(x2) & of(x2,x1) & n_male(x1) & Actor(e1,x1) & v_show(e1) & n_skateboarder(x1))