A very fit man is leaning against a tree.
A man is waiting for a bus in the shade of a tree.
A man can lean on a tree without being in the shade.  A man can lean on a tree for reasons other than waiting for a bus.
exists e1 s1 x1 x2.(against(e1,x2) & n_tree(x2) & Actor(e1,x1) & v_lean(e1) & n_man(x1) & a_fit(s1) & Theme(s1,x1) & r_very(x1))
exists e1 x1 x2 x3 x4.(n_shade(x3) & for(e1,x2) & in(x2,x3) & of(x3,x4) & n_tree(x4) & n_bus(x2) & Actor(e1,x1) & v_wait(e1) & n_man(x1))