The basic idea underlying cardiorespiratory or aerobic training is to place greater demands on the than what’s required during rest. a. muscles b. lungs c. heart d. arteries

avoiding recreational drugs instead of using them

well when looking at this if you think about it   negativley and positivley   react with each other and when the first layer gets full they add layers it starts with 2 on the first layer and it constantly goes on until the official number is there