An officer is standing by an important building
This policeman is on gaurd because of a bomb threat.
We don't know necessarily if there is a bomb threat.
exists e1 s1 x1 x2.(by(e1,x2) & n_building(x2) & a_important(s1) & Theme(s1,x2) & Actor(e1,x1) & v_stand(e1) & n_officer(x1))
exists p1 x1 x2 x3.(n_policeman(x1) & of(p1,x2) & n_threat(x2) & of(x2,x3) & n_bomb(x3) & r_because(p1) & exists x4.(on(x1,x4) & n_gaurd(x4)))