The boy is in the swimming pool.
The boy is swimming in the lake.
Pool and lake are different.
exists p1 x1 x2 x3.(n_pool(x2) & of(x2,x3) & n_swimming(x3) & n_boy(x1) & in(x1,x2))
exists e1 x1 x2.(n_lake(x2) & n_boy(x1) & in(e1,x2) & Actor(e1,x1) & v_swim(e1))