A girl goes down a red slide.
A girl is on a slide
The girl must be on the slide in order to go down it. Red is just an adjective describing the slide.
exists e1 s1 s2 x1 x2.(a_down(s2) & Manner(e1,s2) & Theme(e1,x2) & Actor(e1,x1) & v_go(e1) & n_slide(x2) & a_red(s1) & Theme(s1,x2) & n_girl(x1))
exists p1 x1.(exists x2.(on(x1,x2) & n_slide(x2)) & n_girl(x1))