A man riding a snow machine topples over.
The snow mobile remained upright.
The vehicle cannot have remained upright while it topples over.
exists e1 s1 x1 x2 x3 x4 x5.(a_topic(x1) & a_over(s1) & Manner(e1,s1) & Theme(e1,x3) & Actor(e1,x2) & v_ride(e1) & n_topple(x3) & of(x3,x5) & n_machine(x5) & of(x3,x4) & n_snow(x4) & (x1 = x2) & n_man(x1))
exists e1 p1 s1 x1.(n_snow(x1) & a_mobile(s1) & Manner(e1,s1) & exists s2.(Theme(s2,x1) & a_upright(s2)) & Topic(e1,p1) & Actor(e1,x1) & v_remain(e1))