you are likely to find Tap in/at/on Sink. Tap is related to Call. 
System is related to Age. Age is related to Birthday. Birthday is related to Meaning. Moral is a type of Meaning. 
Sink <--AtLocation-- Tap <--RelatedTo--> Call 
System <--RelatedTo--> Age <--RelatedTo--> Birthday <--RelatedTo--> Meaning <--IsA-- Moral 