a. because id she keeps excerising more and more she could pass out, get a heat stroke, or could possibly get cardiovascular diases sorry i just woke up so if i spelt anything wrong please tell me
 
        
             
        
        
        
I run on the treadmill for cardio than just do normal stretching<span>
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Answer:
Blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium. The pulmonary vein empties oxygen-rich blood, from the lungs into the left atrium.
Explanation:
hope this helps...
and if u didn't get it its veins...
 
        
             
        
        
        
1) Social equality, harmony are necessary for human health. 2) Public cleanliness or sanitation or hygiene is very important for individual health. Hope this is helpful to you
        
                    
             
        
        
        
Brain power is the correct answer.