Three men on a dirty river.
College buddies are river rafting.
Men may not be college buddies. The persons can be in water without rafting.
exists x1 x2 x3.(a_topic(x1) & on(x1,x2) & n_river(x2) & of(x2,x3) & n_dirty(x3) & n_man(x1) & card_eq_3(x1))
exists e1 x1 x2 x3.(Time(e1,x3) & n_river(x3) & Actor(e1,x1) & v_raft(e1) & n_buddy(x1) & (x1 = x2) & ne_nam_college(x2))