Alone is the opposite of Crowd. Crowd is a synonym of Crew. 
Must is related to Due. Due is related to Limit. Limit is related to Highway. Highway is related to Coast. 
Alone <--Antonym--> Crowd <--Synonym--> Crew 
Must <--RelatedTo--> Due <--RelatedTo--> Limit <--RelatedTo--> Highway <--RelatedTo--> Coast 