A man surfing.
A girl is kayaking.
It is either a man or a girl. They are either surfing or kayaking.
exists x1 x2.(a_topic(x1) & n_surfing(x1) & of(x1,x2) & n_man(x2))
exists e1 x1.(Actor(e1,x1) & v_kayake(e1) & n_girl(x1))