Slope is related to Area. Area is related to Hall. Hall is related to Corridor. 
Floor is related to Room. Room is related to Sky. you are likely to find Dust in/at/on Sky. you are likely to find Dust in/at/on Plate. 
Slope <--RelatedTo--> Area <--RelatedTo--> Hall <--RelatedTo--> Corridor 
Floor <--RelatedTo--> Room <--RelatedTo--> Sky <--AtLocation-- Dust --AtLocation--> Plate 