Two workers are building a skyscraper.
A couple of workers are building a very tall building.
"Two" means couple. A skyscraper is a tall building. So a couple of workers building a tall building means they are most likely two workers building a skyscraper.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_build(e1) & n_skyscraper(x2) & n_worker(x1) & card_eq_2(x1))
exists e1 s1 x1 x2 x3.(Theme(e1,x3) & Actor(e1,x1) & v_build(e1) & n_building(x3) & a_tall(s1) & Theme(s1,x3) & r_very(x3) & of(x1,x2) & n_worker(x2) & n_couple(x1))