One man is riding his motorcycle in a desert.
A man is riding a motocycle by cactuses.
There may just be sand, there's no guarantee of cactuses.
exists e1 x1 x2 x3.(in(e1,x2) & n_desert(x2) & Theme(e1,x3) & Actor(e1,x1) & v_ride(e1) & n_motorcycle(x3) & of(x3,x2) & n_male(x2) & n_man(x1) & card_eq_1(x1))
exists e1 x1 x2 x3.(by(e1,x3) & n_cactus(x3) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_motocycle(x2) & n_man(x1))