A man in a gray shirt jumps over the top of a sand dune in the desert.
A man fell off his bike.
Someone who jumps doesn't necessarily qualify as being in the act of falling off something.
exists s1 x1 x2 x3 x4 x5 x6 x7.(n_desert(x7) & n_top(x4) & a_topic(x1) & over(x1,x4) & of(x4,x5) & in(x5,x7) & n_dune(x5) & of(x5,x6) & n_sand(x6) & in(x1,x2) & n_jump(x2) & of(x2,x3) & n_shirt(x3) & a_gray(s1) & Theme(s1,x2) & n_man(x1))
exists e1 s1 x1 x2.(a_off(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_fall(e1) & n_bike(x2) & of(x2,x1) & n_male(x1) & n_man(x1))