Answer:
Sewage treatment generally involves three stages, called primary, secondary and tertiary treatment. Primary treatment consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface.
Explanation:
Hope that helps:)
 
        
             
        
        
        
left one going up is evaporation. top one is condensation. the one next to that is precipitation. then I forgot the other too, sorry.
 
        
             
        
        
        
The other biologists and scientists thought his theories were bogus
        
                    
             
        
        
        
Carbon dioxide and oxygen