you are likely to find Closet in/at/on School. you are likely to find Doll in/at/on Closet. Doll is related to Box. 
Fraction is a type of Chemical. Drug is a type of Chemical. Drug is related to Blow. 
School <--AtLocation-- Closet <--AtLocation-- Doll <--RelatedTo--> Box 
Fraction --IsA--> Chemical <--IsA-- Drug <--RelatedTo--> Blow 