Adult and child observe fish tank.
two people watching a snake
Observing a fish tank is not watching a snake.
exists s1 x1 x2 x3 x4 x5.(n_tank(x1) & of(x1,x5) & n_fish(x5) & of(x1,x4) & n_observe(x4) & of(x1,x3) & n_child(x3) & a_.(s1) & Theme(s1,x1) & of(x1,x2) & n_adult(x2) & a_topic(x1))
exists e1 x1 x2 x3.(a_topic(x1) & Theme(e1,x3) & Actor(e1,x2) & v_watch(e1) & n_snake(x3) & (x1 = x2) & n_people(x1) & card_eq_2(x1))