The workers prepare the large tube for hauling.
The workers are preparing a sewer line.
large tube doesn't always mean  sewer line.
exists e1 s1 x1 x2 x3.(n_tube(x2) & a_large(s1) & Theme(s1,x2) & n_worker(x1) & for(e1,x3) & n_hauling(x3) & Theme(e1,x2) & Actor(e1,x1) & v_prepare(e1))
exists e1 x1 x2 x3.(n_worker(x1) & Theme(e1,x2) & Actor(e1,x1) & v_prepare(e1) & n_line(x2) & of(x2,x3) & n_sewer(x3))