A person is dirt biking.
a young man falls off his dirt bike
Sentence 1 does not tell us that the person is a man, is young, or has fallen off his bike.
exists p1 x1.(exists s1 x2.((x1 = x2) & n_biking(x2) & a_dirt(s1) & Theme(s1,x2)) & n_person(x1))
exists e1 s1 s2 x1 x2 x3.(a_off(s2) & Manner(e1,s2) & Theme(e1,x2) & Actor(e1,x1) & v_fall(e1) & n_bike(x2) & of(x2,x3) & n_dirt(x3) & of(x2,x1) & n_male(x1) & n_man(x1) & a_young(s1) & Theme(s1,x1))