Knife can be used for Butter. Butter is a type of Grocery. Grocery is related to Sack. 
Box is related to Speaker. you are likely to find Speaker in/at/on Conference. you are likely to find Confusion in/at/on Conference. Confusion is related to Mind. 
Knife --UsedFor--> Butter --IsA--> Grocery <--RelatedTo--> Sack 
Box <--RelatedTo--> Speaker --AtLocation--> Conference <--AtLocation-- Confusion <--RelatedTo--> Mind 