A group of people sale on a lake with houses in the background.
A group of people sailing.
Going on a sail on a lake is same as sailing.
exists x1 x2 x3 x4 x5 x6.(n_background(x6) & a_topic(x1) & on(x1,x4) & with(x4,x5) & in(x5,x6) & n_house(x5) & n_lake(x4) & of(x1,x2) & Time(x2,x3) & n_sale(x3) & n_people(x2) & n_group(x1))
exists x1 x2 x3.(a_topic(x1) & of(x1,x2) & Time(x2,x3) & n_sailing(x3) & n_people(x2) & n_group(x1))