These people are doing dangerous things.
People are riding motorcycles without helmets.
There are other dangerous things that people do beside riding motorcycles without helmets.
exists e1 s1 x1 x2.(n_people(x1) & Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & n_thing(x2) & a_dangerous(s1) & Theme(s1,x2))
exists e1 x1 x2.(-exists x3.(with(e1,x3) & n_helmet(x3)) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_motorcycle(x2) & n_people(x1))