Two officers enjoy stand by as a crowd has gathered behind a barricade.
Two officers stand by as a riot breaks out.
the first sentence doesn't convey what the crowd is gathered for and it turns out it was a riot
exists e1 e2 s1 x1 x2 x3 x4 x5.(as(e1,x3) & behind(e2,x5) & n_barricade(x5) & Actor(e2,x4) & v_gather(e2) & (x3 = x4) & n_crowd(x3) & a_by(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_enjoy(e1) & n_stand(x2) & n_officer(x1) & card_eq_2(x1))
exists e1 e2 s1 s2 x1 x2 x3.(a_by(s2) & Manner(e1,s2) & as(e1,x2) & a_out(s1) & Manner(e2,s1) & Actor(e2,x3) & v_break(e2) & (x2 = x3) & n_riot(x2) & Actor(e1,x1) & v_stand(e1) & n_officer(x1) & card_eq_2(x1))