Hi there!
Sustainability means that something or someone has the ability to keep something going. 
For example, a plant could have good life sustainability because it has a special poison, keeping predators away from it.
You could be self sustainable by growing your own crops, collecting your own water, and making things you need.
Hope this helps!
        
                    
             
        
        
        
Answer:
When they slide down, they lose this potential energy, which turns into kinetic energy and thermal energy. Thermal Energy - This energy is related to the temperature of a body or a system. When friction is involved in a system, part of the kinetic energy is transformed into thermal energy.
 
        
             
        
        
        
Answer:
Make up the skull and composed of the brain 
Explanation:
 
        
             
        
        
        
Answer: The answer would be Substrates
 
        
                    
             
        
        
        
Let me help you, 
The process in which two gametes unite is called fertilization. 
Have a good one!