A man is kayaking down a waterfall.
A man is kayaking on a still lake.
A man cannot be kayaking down a waterfall and on a still lake at the same time.
exists e1 s1 x1 x2.(a_down(s1) & Manner(e1,s1) & Theme(e1,x2) & Actor(e1,x1) & v_kayake(e1) & n_waterfall(x2) & n_man(x1))
exists e1 s1 x1 x2.(on(e1,x2) & n_lake(x2) & a_still(s1) & Theme(s1,x2) & Actor(e1,x1) & v_kayake(e1) & n_man(x1))