A skateboarder uses a ramp.
A person is participating in an activity.
a skateboarder using a ramp implies he is participating in an activity.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_use(e1) & n_ramp(x2) & n_skateboarder(x1))
exists e1 x1 x2.(in(e1,x2) & n_activity(x2) & Actor(e1,x1) & v_participate(e1) & n_person(x1))