A person in red and white doing a midair trick on their dirt bike.
A person is practicing his tricks.
A person doing a trick doesn't have to be practicing.  He could be competing.  And he doesn't have to be doing more than one tricks.
exists e1 s1 x1 x2 x3 x4 x5 x6 x7.(a_topic(x1) & Theme(e1,x4) & Actor(e1,x3) & v_do(e1) & on(x4,x6) & n_bike(x6) & of(x6,x7) & n_dirt(x7) & of(x6,x1) & n_thing(x1) & n_trick(x4) & of(x4,x5) & n_midair(x5) & (x1 = x3) & in(x1,x2) & n_white(x2) & a_red(s1) & Theme(s1,x2) & n_person(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_practice(e1) & n_trick(x2) & of(x2,x1) & n_male(x1) & n_person(x1))