Man is on his bike in the dirt.
A man is riding a bike in the dirt.
On the bike means he is riding it
exists p1 x1 x2 x3.(n_dirt(x3) & on(x1,x2) & in(x2,x3) & n_bike(x2) & of(x2,x1) & n_male(x1) & n_man(x1))
exists e1 x1 x2 x3.(n_dirt(x3) & in(e1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_bike(x2) & n_man(x1))