Two people picking up trash on the side of the road.
Three people are dropping trash by the side of the road.
Two is not three.  One cannot be dropping trash and picking up trash at the same time.
exists e1 s1 x1 x2 x3 x4 x5.(n_road(x5) & n_side(x4) & a_topic(x1) & a_up(s1) & Manner(e1,s1) & Theme(e1,x3) & Actor(e1,x2) & v_pick(e1) & on(x3,x4) & of(x4,x5) & n_trash(x3) & (x1 = x2) & n_people(x1) & card_eq_2(x1))
exists e1 x1 x2 x3 x4.(n_road(x4) & n_side(x3) & by(e1,x3) & of(x3,x4) & Time(e1,x2) & n_trash(x2) & Actor(e1,x1) & v_drop(e1) & n_people(x1) & card_eq_3(x1))