Begin is related to Keep. Keep is a synonym of Observe. 
Toll is related to Booth. Booth is related to Structure. Structure is related to Monument. Monument is related to Grave. 
Begin <--RelatedTo--> Keep <--Synonym--> Observe 
Toll <--RelatedTo--> Booth <--RelatedTo--> Structure <--RelatedTo--> Monument <--RelatedTo--> Grave 