Gray is related to Cloud. you are likely to find Cloud in/at/on Atmosphere. Fog is a type of Atmosphere. Fog is related to Thick. 
City is part of Province. you are likely to find Bureau in/at/on City. Bureau is related to French. 
Gray <--RelatedTo--> Cloud --AtLocation--> Atmosphere <--IsA-- Fog <--RelatedTo--> Thick 
Province <--PartOf-- City <--AtLocation-- Bureau <--RelatedTo--> French 