Shell is related to Defense. Apology is a type of Defense. 
Walking can be used for Pleasure. Walking is related to Human. Human is related to Ill. Ill is related to Fever. 
Shell <--RelatedTo--> Defense <--IsA-- Apology 
Pleasure <--UsedFor-- Walking <--RelatedTo--> Human <--RelatedTo--> Ill <--RelatedTo--> Fever 