A dog drinking from a creek.
A dog is drinking.
Both sentences explain that a dog is drinking.
exists x1 x2 x3.(a_topic(x1) & from(x1,x3) & n_creek(x3) & n_drinking(x1) & of(x1,x2) & n_dog(x2))
exists p1 x1.(exists x2.((x1 = x2) & n_drinking(x2)) & n_dog(x1))