Rat is related to Long. Long is the opposite of Short. Short is related to Crew. Crew is related to Army. 
Hard is related to Iron. Iron is related to Handle. 
Rat <--RelatedTo--> Long <--Antonym--> Short <--RelatedTo--> Crew <--RelatedTo--> Army 
Hard <--RelatedTo--> Iron <--RelatedTo--> Handle 