31c-11c=20c So, therefore, the range is 20c.
Hope this helps! :D
        
                    
             
        
        
        
Answer:
objective lenses
Explanation:
objective lenses with different magnifications, screwed into a circular "nosepiece" which may be rotated to select the required lens.
 
        
             
        
        
        
Answer:
It's C. They are mostly made up of hydrogen and helium 
 
        
             
        
        
        
Explanation:
The pulmonary valve (sometimes referred to as the pulmonic valve) is a valve of the heart that lies between the right ventricle and the pulmonary artery and has three cusps. It is one of the four valves of the heart and one of the two semilunar valves, the other being the aortic valve. Similar to the aortic valve, the pulmonary valve opens in ventricular systole, when the pressure in the right ventricle rises above the pressure in the pulmonary artery. At the end of ventricular systole, when the pressure in the right ventricle falls rapidly, the pressure in the pulmonary artery will close the pulmonary valve. 
 
        
             
        
        
        
Well depending on what the environmental change is the organisms will have to adapt, or move. if they don't they may not survive.
comment if you want an example or 2