What kind of sports impressed you most during your childhood? Maybe racing around the playground or skipping rope for hours would bring you pleasure. At that time you weren't thinking of fitness, you were just thinking of entertainment. But in this age of high-tech home equipment and underused gym memberships, the simple joy of jumping rope has been forgotten. I think rediscovering it probably will give you a total-body exercise. Although considered an excellent form of exercise, jumping rope has never received widespread acceptance because of two reasons. First,most people recognize jumping rope as an excellent form of cardiovascular   exercise, but they also believe that it is simply too difficult. In other words, they don't think they'll be able to continue jumping for the near 20 minutes in order to achieve a beneficial physical effect. Second, many regard it as somewhat boring and overly repetitive --not as something fun or enjoyable.  _ . Instead of doing the usual two-foot bounce  over and over again, players good at rope-jumping often change their pattern every 10 or 20 jumps. A single bounce, a double -bounce , a skip, a knee-up, side swings , as well as a variety of other easy-to-learn free-style rope-jumping . Nowadays researchers are discovering that jumping rope also prepares the brain for learning . It is an exercise allowing both brain hemispheres to perform equallyto each other . In short, jumping rope can be a life-long activity requiring little equipment, time and space , yet leading to a much healthier life. One reason that can explain why rope jumping has not spread widely is that  _  .
it benefits the cardiovascular system it is too difficult for people to learn to jump it is believed to be boring and repetitive it requires little equipment, time and space
Question: What kind of sports impressed you most during your childhood? Maybe racing around the playground or skipping rope for hours would bring you pleasure. At that time you weren't thinking of fitness, you were just thinking of entertainment. But in this age of high-tech home equipment and underused gym memberships, the simple joy of jumping rope has been forgotten. I think rediscovering it probably will give you a total-body exercise. Although considered an excellent form of exercise, jumping rope has never received widespread acceptance because of two reasons. First,most people recognize jumping rope as an excellent form of cardiovascular   exercise, but they also believe that it is simply too difficult. In other words, they don't think they'll be able to continue jumping for the near 20 minutes in order to achieve a beneficial physical effect. Second, many regard it as somewhat boring and overly repetitive --not as something fun or enjoyable.  _ . Instead of doing the usual two-foot bounce  over and over again, players good at rope-jumping often change their pattern every 10 or 20 jumps. A single bounce, a double -bounce , a skip, a knee-up, side swings , as well as a variety of other easy-to-learn free-style rope-jumping . Nowadays researchers are discovering that jumping rope also prepares the brain for learning . It is an exercise allowing both brain hemispheres to perform equallyto each other . In short, jumping rope can be a life-long activity requiring little equipment, time and space , yet leading to a much healthier life. One reason that can explain why rope jumping has not spread widely is that  _  .
A. it benefits the cardiovascular system
B. it is too difficult for people to learn to jump
C. it is believed to be boring and repetitive
D. it requires little equipment, time and space
Answer: