A skateboarder flies off the stairs.
A person skateboarding.
A person can be a skateboarder
exists e1 s1 x1 x2.(n_stair(x2) & a_off(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_fly(e1) & n_skateboarder(x1))
exists x1 x2.(a_topic(x1) & Time(x1,x2) & n_skateboarding(x2) & n_person(x1))