The boy is in the swimming pool.
The boy is swimming in the pool.
Just because the boy is in the pool, it doesn't mean he is swimming.
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_pool(x2) & n_boy(x1) & in(e1,x2) & Actor(e1,x1) & v_swim(e1))