Gray is related to Newspaper. Sun is a type of Newspaper. 
Bulb is related to Light. Light is related to Window. Window is related to Sorry. Sorry is related to Apology. 
Gray <--RelatedTo--> Newspaper <--IsA-- Sun 
Bulb <--RelatedTo--> Light <--RelatedTo--> Window <--RelatedTo--> Sorry <--RelatedTo--> Apology 