a bmx rider gets a lot of air.
A person is sitting in the bleachers.
The two sentences are not talking about the same person. The bmx rider getting air is clearly not sitting in the bleachers.
exists e1 x1 x2 x3 x4.(Theme(e1,x3) & Actor(e1,x1) & v_get(e1) & of(x3,x4) & n_air(x4) & n_lot(x3) & n_rider(x1) & of(x1,x2) & n_bmx(x2))
exists e1 x1 x2.(n_bleacher(x2) & in(e1,x2) & Actor(e1,x1) & v_sit(e1) & n_person(x1))