Bikers race through a forest.
Some guys are going through a hilly forest on bikes.
Bikers doesn't imply gender. Forests can be hilly or flat.
exists x1 x2 x3.(a_topic(x1) & through(x1,x3) & n_forest(x3) & n_race(x1) & of(x1,x2) & n_biker(x2))
exists e1 s1 x1 x2 x3.(through(e1,x2) & on(x2,x3) & n_bike(x3) & n_forest(x2) & a_hilly(s1) & Theme(s1,x2) & Actor(e1,x1) & v_go(e1) & n_guy(x1))