Power is related to Engine. Engine is related to Internal. Internal is the opposite of External. External is a synonym of International. 
Average is the opposite of Special. Special is related to Ability. Ability is related to Afford. Afford is related to Able. 
Power <--RelatedTo--> Engine <--RelatedTo--> Internal <--Antonym--> External <--Synonym--> International 
Average <--Antonym--> Special <--RelatedTo--> Ability <--RelatedTo--> Afford <--RelatedTo--> Able 