Street is related to Black. Black is related to Disease. Disease is related to Deadly. 
Must is related to Old. Old is related to Variety. Variety is a synonym of Description. Description is related to Hard. 
Street <--RelatedTo--> Black <--RelatedTo--> Disease <--RelatedTo--> Deadly 
Must <--RelatedTo--> Old <--RelatedTo--> Variety <--Synonym--> Description <--RelatedTo--> Hard 