A lot of people are marching through the street.
A crowd is marching down the street.
A lot of people could be called a crowd and through the street and down the street are equivalent expressions.
exists e1 x1 x2 x3.(n_street(x3) & through(e1,x3) & Actor(e1,x1) & v_march(e1) & of(x1,x2) & n_people(x2) & n_lot(x1))
exists e1 s1 x1 x2.(n_street(x2) & a_down(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_march(e1) & n_crowd(x1))