People marching on the grass in yellow shirts carrying drums
A marching band is practicing .
People marching on the grass don't necessarily imply they are a band.
exists e2 e1 s1 x1 x2 x3 x4 x5 x6.(n_grass(x3) & a_topic(x1) & on(e1,x3) & in(x3,x4) & Theme(e2,x6) & Actor(e2,x5) & v_carry(e2) & n_drum(x6) & (x4 = x5) & n_shirt(x4) & a_yellow(s1) & Theme(s1,x4) & Actor(e1,x2) & v_march(e1) & (x1 = x2) & n_people(x1))
exists e1 e2 x1.(Actor(e2,x1) & v_practice(e2) & n_band(x1) & Actor(e1,x1) & v_march(e1))