A person rides his mountain bike down a steep hill in the woods.
He is riding in a race.
You can ride a mountain bike and not be in a race.
exists e1 s1 x1 x2 x3 x4 x5.(n_wood(x5) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & down(x2,x4) & in(x4,x5) & n_hill(x4) & a_steep(s1) & Theme(s1,x4) & n_bike(x2) & of(x2,x3) & n_mountain(x3) & of(x2,x1) & n_male(x1) & n_person(x1))
exists e1 x1.(in(e1,x1) & n_race(x1) & Actor(e1,x1) & v_ride(e1) & n_male(x1))