Dry is related to Fly. Fly is a type of Opening. Opening is the opposite of Cover. Mask is a type of Cover. 
Purpose is a synonym of Mean. Mean is a synonym of Cruel. 
Dry <--RelatedTo--> Fly --IsA--> Opening <--Antonym--> Cover <--IsA-- Mask 
Purpose <--Synonym--> Mean <--Synonym--> Cruel 