Hard is related to Board. Board is a type of Sheet. Sheet is a type of Line. Line is a synonym of Contrast. 
Likely is related to Possible. Possible is related to Accomplish. 
Hard <--RelatedTo--> Board --IsA--> Sheet --IsA--> Line <--Synonym--> Contrast 
Likely <--RelatedTo--> Possible <--RelatedTo--> Accomplish 