A man waterskies.
A guy is riding a bike.
Activities are different, one cannot ride a bike and water ski.
exists x1 x2.(a_topic(x1) & n_watersky(x1) & of(x1,x2) & n_man(x2))
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_bike(x2) & n_guy(x1))