Spectators look on in amazement as a basketball player dunks the ball.
People watch basketaball.
Spectators are people, and they look, which is another way of saying watch. They are watching a basketball player, therefore they are watching basketball.
exists e1 p1 x1 x2 x5.(n_ball(x5) & exists e2 x3 x4.(Theme(e2,x5) & Actor(e2,x3) & v_dunk(e2) & n_player(x3) & of(x3,x4) & n_basketball(x4)) & as(e1,p1) & r_on(e1) & in(e1,x2) & n_amazement(x2) & Actor(e1,x1) & v_look(e1) & n_spectator(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_watch(e1) & n_basketaball(x2) & n_people(x1))