Wood is related to Bird. you are likely to find Bird in/at/on Roof. 
White is related to Gray. Gray is related to Fog. Fog is related to Water. Water is related to Necessity. 
Wood <--RelatedTo--> Bird --AtLocation--> Roof 
White <--RelatedTo--> Gray <--RelatedTo--> Fog <--RelatedTo--> Water <--RelatedTo--> Necessity 