Oak is a type of Wood. Wood is the opposite of Stone. you are likely to find Stone in/at/on Cave. you are likely to find Entrance in/at/on Cave. 
Fork is a type of Tool. Tool is related to Soap. 
Oak --IsA--> Wood <--Antonym--> Stone --AtLocation--> Cave <--AtLocation-- Entrance 
Fork --IsA--> Tool <--RelatedTo--> Soap 