People sit on the curb watching an event.
People watching sports
Just because people sit on the curb watching an event doesn't necessarily mean the event is sports.
exists e2 e1 x1 x2 x3.(n_curb(x2) & for(e1,e2) & Theme(e2,x3) & Actor(e2,x1) & v_watch(e2) & n_event(x3) & on(e1,x2) & Actor(e1,x1) & v_sit(e1) & n_people(x1))
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_watch(e1) & n_sport(x3) & (x1 = x2) & n_people(x1))