Two people are observing some ruins.
A man and a woman are swimming in the lake.
A man and a woman cannot observe ruins while swimming in the lake.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_observe(e1) & n_ruin(x2) & n_people(x1) & card_eq_2(x1))
exists e1 x1 x2 x3 x4.(n_lake(x4) & in(e1,x4) & Actor(e1,x1) & v_swim(e1) & subset_of(x3,x1) & n_woman(x3) & subset_of(x2,x1) & n_man(x2))