Man on a dirt bike
The man is practicing his runs.
Just because a man is on a dirt bike does not mean he is practicing his runs.
exists x1 x2 x3.(a_topic(x1) & on(x1,x2) & n_bike(x2) & of(x2,x3) & n_dirt(x3) & n_man(x1))
exists e1 x1 x2.(n_run(x2) & of(x2,x1) & n_male(x1) & n_man(x1) & Theme(e1,x2) & Actor(e1,x1) & v_practice(e1))