an umpire makes a mark on a base on the field.
People are playing baseball.
Just because an umpire makes a mark on a base on the field does not mean they are playing baseball. The umpire may just be marking the bases for a game tomorrow.
exists e1 x1 x2 x3 x4.(n_field(x4) & Theme(e1,x2) & Actor(e1,x1) & v_make(e1) & on(x2,x3) & on(x3,x4) & n_base(x3) & n_mark(x2) & n_umpire(x1))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_baseball(x2) & n_people(x1))