People are riding around on snowmobiles.
It is still snowing while they ride their snowmobiles
Not all people riding around on snowmobiles do so while it's still snowing.
exists e1 x1 x2.(r_around(e1) & on(e1,x2) & n_snowmobile(x2) & Actor(e1,x1) & v_ride(e1) & n_people(x1))
exists e1 p1 s1 x1 x2.(n_snowmobile(x2) & of(x2,x1) & n_thing(x1) & n_thing(x1) & n_thing(x1) & a_still(s1) & Manner(e1,s1) & exists e2.(Theme(e2,x2) & Actor(e2,x1) & v_ride(e2)) & while(e1,p1) & Actor(e1,x1) & v_snow(e1))