Two doctors perform an operation.
The doctors are washing their clothes.
Doctors would never be washing their clothes while performing an operation.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_perform(e1) & n_operation(x2) & n_doctor(x1) & card_eq_2(x1))
exists e1 x1 x2.(n_clothes(x2) & of(x2,x1) & n_thing(x1) & n_doctor(x1) & Theme(e1,x2) & Actor(e1,x1) & v_wash(e1))