A boy carries a box across a bridge.
The bridge cannot be crossed.
one bridge is being crossed while the other bridge can not be crossed
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_carry(e1) & across(x2,x3) & n_bridge(x3) & n_box(x2) & n_boy(x1))
exists x1.(n_bridge(x1) & -exists e1 p1.(exists e2.(Theme(e2,x1) & v_cross(e2)) & Topic(e1,p1) & Actor(e1,x1) & v_can(e1)))