Sorry is a synonym of Sad. Sad is related to Frown. Frown is related to Expression. Expression is a synonym of Formula. 
Computer can be used for Work. Computer is a type of Tool. 
Sorry <--Synonym--> Sad <--RelatedTo--> Frown <--RelatedTo--> Expression <--Synonym--> Formula 
Work <--UsedFor-- Computer --IsA--> Tool 