Stars are formed in clouds of dust and gas (nebulae.) Nuclear reactions at the center (core) of stars gives enough energy to make them shine brightly for many, many years. The exact l<span>ifetime of a star depends on its size.</span>
        
                    
             
        
        
        
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Blood vessel, a vessel in the human or animal body in which blood circulates. The vessels that carry blood away from the heart are called arteries, and their very small branches are arterioles. Very small branches that collect the blood from the various organs and parts are called venules, and they unite to form veins, which return the blood to the heart. Capillaries are minute thin-walled vessels that connect the arterioles and venules; it is through the capillaries that nutrients and wastes are exchanged between the blood and body tissues.
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the answer is pioneer species 
 
        
             
        
        
        
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the heat in the classroom made him feel faint so he asked permission to exit
Copper is a good medium for the conduction of heat and electricity
These fires create convection funnels, and throw a lot of particles into the upper atmosphere
The sun, a lamp, or an electric heater all warm us by radiation
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