The teenagers are performing tricks on their bicycles at night.
Some teens are riding bikes at night.
One has to ride a bicycle to perform tricks on it.
exists e1 x1 x2 x3 x4.(n_bicycle(x3) & of(x3,x1) & n_thing(x1) & n_teenager(x1) & at(e1,x4) & n_night(x4) & on(e1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_perform(e1) & n_trick(x2))
exists e1 x1 x2 x3.(at(e1,x3) & n_night(x3) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_bike(x2) & n_teens(x1))