Later is the opposite of Previous. Previous is similar to Past. Past is related to Old. Old is related to Birthday. 
Screening is a type of Testing. Screening is a form of Screen. Screen is related to Smoke. Smoke is related to Toxic. 
Later <--Antonym--> Previous <--SimilarTo--> Past <--RelatedTo--> Old <--RelatedTo--> Birthday 
Testing <--IsA-- Screening --FormOf--> Screen <--RelatedTo--> Smoke <--RelatedTo--> Toxic 