Dogs are pulling a sled across the snow.
The sled is being pulled across the snow by a pack of dogs.
A Pack of dogs are dogs, when pulling a sled a sled must be pulled.
exists e1 x1 x2 x3.(n_snow(x3) & across(e1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_pull(e1) & n_sled(x2) & n_dog(x1))
exists e1 x1 x2 x3 x4.(n_snow(x2) & n_sled(x1) & Actor(e1,x3) & of(x3,x4) & n_dog(x4) & n_pack(x3) & across(e1,x2) & Theme(e1,x1) & v_pull(e1))