Oregon percussionists are marching with the band.
There is marching.
Percussionists marching mean there is marching. One is verb, one is a noun.
exists e1 x1 x2 x3.(n_band(x3) & with(e1,x3) & Actor(e1,x1) & v_march(e1) & n_percussionist(x1) & (x1 = x2) & ne_per_oregon(x2))
exists p1 x1 x2.((x1 = x2) & n_march(x2))