Ground is related to Gravity. Sun can be used for Gravity. 
Flow is related to Do. Do is related to Cry. Cry is related to Week. Week is the opposite of Month. 
Ground <--RelatedTo--> Gravity <--UsedFor-- Sun 
Flow <--RelatedTo--> Do <--RelatedTo--> Cry <--RelatedTo--> Week <--Antonym--> Month 