1.They awarded the medal to the hero.
Preposition: to the hero
Object of the preposition: hero
2.The pirates buried the treasure inside the cave.
Preposition: inside the cave
Object of the preposition: cave
3.Joan is the owner of the expensive necklace.
Preposition: of the expensive necklace
Object of the preposition: necklace
4.Within the hour I will finish my homework.
Preposition: within the hour
Object of the preposition: hour
5.My cottage is behind the house.
Preposition: behind the house
Object of the preposition: house