Teenager rides through the forest on his mountain bike.
The teenager is on a mountain bike.
Riding through the forest on a mountain bike requires that one be on a mountain bike.
exists e1 x1 x2 x3 x4.(n_bike(x3) & of(x3,x4) & n_mountain(x4) & of(x3,x2) & n_male(x2) & n_forest(x2) & ne_nam_teenager(x1) & on(e1,x3) & through(e1,x2) & Actor(e1,x1) & v_ride(e1))
exists p1 x1.(n_teenager(x1) & exists x2 x3.(on(x1,x2) & n_bike(x2) & of(x2,x3) & n_mountain(x3)))