Verbal is the opposite of Written. Written is related to Writing. Writing is a type of Skill. 
Hypothesis is related to Essay. Essay is related to Report. Report is a synonym of Cover. 
Verbal <--Antonym--> Written <--RelatedTo--> Writing --IsA--> Skill 
Hypothesis <--RelatedTo--> Essay <--RelatedTo--> Report <--Synonym--> Cover 