you are likely to find River in/at/on Continent. Aid is a type of River. Aids is a form of Aid. 
Excellent is related to Great. Great is the opposite of Awful. Awful is a synonym of Tremendous. 
Continent <--AtLocation-- River <--IsA-- Aid <--FormOf-- Aids 
Excellent <--RelatedTo--> Great <--Antonym--> Awful <--Synonym--> Tremendous 