Possibility is related to Might. Might is the opposite of Weak. 
Extensive is a synonym of Extended. Extended is related to Stretch. Person wants (to) Stretch. Person does not want (to) Shut. 
Possibility <--RelatedTo--> Might <--Antonym--> Weak 
Extensive <--Synonym--> Extended <--RelatedTo--> Stretch <--Desires-- Person --NotDesires--> Shut 