Swim is related to Shark. Shark is related to Fierce. 
you are likely to find Disease in/at/on Hospital. Disease is related to Fatal. Fatal is a synonym of Inevitable. Inevitable is the opposite of Impossible. 
Swim <--RelatedTo--> Shark <--RelatedTo--> Fierce 
Hospital <--AtLocation-- Disease <--RelatedTo--> Fatal <--Synonym--> Inevitable <--Antonym--> Impossible 