A group of people are riding bikes across a bridge.
a bike thief walks silently in an alley
A group of people are either riding bikes are walking silently.
exists e1 x1 x2 x3 x4.(Theme(e1,x3) & Actor(e1,x1) & v_ride(e1) & across(x3,x4) & n_bridge(x4) & n_bike(x3) & of(x1,x2) & n_people(x2) & n_group(x1))
exists e1 s1 x1 x2 x3.(in(e1,x3) & n_alley(x3) & a_silently(s1) & Manner(e1,s1) & Actor(e1,x1) & v_walk(e1) & n_thief(x1) & of(x1,x2) & n_bike(x2))