Two surgeons performing a surgery.
The surgeons had been in surgery for hours.
Surgeons performing a surgery may have just started and need not have been in surgery for hours.
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_perform(e1) & n_surgery(x3) & (x1 = x2) & n_surgeon(x1) & card_eq_2(x1))
exists p1 x1 x2.(n_surgeon(x1) & for(p1,x2) & n_hour(x2) & exists x3.(in(x1,x3) & n_surgery(x3)))