On the other hand, 'down' could act as a preposition and make a prepositional phrase. Here, down means the direction downward, so the sentence would mean that John will be running downward the road.
Exercise Ⅳ.
(1) (a) Up a huge hill john ran.
(b) *Up a huge bill John ran.
Only whole phrase not just a part of a phrase can be preposed. In the sentence (a), therefore, the prepositi