Children sitting in a canoe on a quiet lake.
Children on a canoe lost their paddle.
The paddle could be in the canoe. Just because you can't see a paddle doesn't mean they lost it.
exists e1 s1 x1 x2 x3 x4.(a_topic(x1) & on(e1,x4) & n_lake(x4) & a_quiet(s1) & Theme(s1,x4) & in(e1,x3) & n_canoe(x3) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_child(x1))
exists e1 x1 x2 x3.(Theme(e1,x3) & Actor(e1,x1) & v_lose(e1) & n_paddle(x3) & of(x3,x1) & n_thing(x1) & on(x1,x2) & n_canoe(x2) & n_child(x1))