Maintain is a synonym of Observe. Observe is related to Scientific. Scientific is related to Matter. Matter is the opposite of Space. 
Homework is a synonym of Preparation. Preparation is related to Practice. Practice is a synonym of Fashion. 
Maintain <--Synonym--> Observe <--RelatedTo--> Scientific <--RelatedTo--> Matter <--Antonym--> Space 
Homework <--Synonym--> Preparation <--RelatedTo--> Practice <--Synonym--> Fashion 