Two blonds are trying to hail a taxi cab.
A pair with light-colored hair is trying to catch a cab.
Two blonds can also be described as 'A pair', also 'trying to catch a cab' is a rephrasing of 'trying to hail a taxi cab'.
exists e1 p1 x1.(Topic(e1,p1) & Actor(e1,x1) & v_try(e1) & exists e2 x2 x3.(Theme(e2,x2) & Actor(e2,x1) & v_hail(e2) & n_cab(x2) & of(x2,x3) & n_taxi(x3)) & n_blond(x1) & card_eq_2(x1))
exists e1 p1 s1 x1 x2.(Topic(e1,p1) & Actor(e1,x1) & v_try(e1) & exists e2 x3.(Theme(e2,x3) & Actor(e2,x1) & v_catch(e2) & n_cab(x3)) & with(x1,x2) & n_hair(x2) & a_light-colored(s1) & Theme(s1,x2) & n_pair(x1))