Basic is related to Letter. Letter is related to Small. Small is related to Troop. 
Ear is the opposite of Eye. Eye is the opposite of Lip. you are likely to find Lip in/at/on Mouth. 
Basic <--RelatedTo--> Letter <--RelatedTo--> Small <--RelatedTo--> Troop 
Ear <--Antonym--> Eye <--Antonym--> Lip --AtLocation--> Mouth 