Cocaine is related to Drug. Drop is a type of Drug. 
Mechanism is related to Bed. Bed is related to Spring. Spring is related to New. New is related to City. 
Cocaine <--RelatedTo--> Drug <--IsA-- Drop 
Mechanism <--RelatedTo--> Bed <--RelatedTo--> Spring <--RelatedTo--> New <--RelatedTo--> City 