Excuse is a synonym of Explain. Explain is related to Justify. Legitimate is a type of Justify. 
Read is related to Subject. Subject is a synonym of Matter. Text is a type of Matter. 
Excuse <--Synonym--> Explain <--RelatedTo--> Justify <--IsA-- Legitimate 
Read <--RelatedTo--> Subject <--Synonym--> Matter <--IsA-- Text 