完形填空,阅读下面短文，掌握其大意，然后从各题所给的四个选项中选出一个最佳答案。
Why exercise？
You’ve probably heard countless times how exercise is “good for you”. But did you know that it can ________ help you feel good? Exercise plays a key role in  ________ healthy. It can strengthen the bones, heart, lungs and muscles. It can also________ the stress and help you sleep better. Experts suggest that teenagers should get 60 minutes or more of physical  ________ each day. Here are some of the reasons:
Exercise benefits（有益）every part of the body, ________the mind. Exercising causes body to produce chemicals that can  ________a person feel more peaceful and happier. It can ________ help some people who have mild mental diseases.  ________ exercising can help you look better. People who exercise burn more energy and look________than those who don’t.
In fact, exercise helps people lose  ________ and lower the risk of some diseases. Exercising to maintain (保持) a healthy weight decreases a  ________ risk of developing certain diseases. These diseases, which  ________ found mostly in adults, are becoming more common in teenagers.
Exercise can help a person age well. This ________  not seem important now, but your body will thank you later. Studies have found that weight-bearing exercise,  ________  jumping, running and walking, can help people keep their ________  strong.
You may not feel like doing exercise regularly, but why not do it due to the above mentioned reasons from now on?

A．quietly B．actually C．recently D．quickly

A．staying B．helping C．giving D．looking

A．keep B．reply C．refuse D．reduce

A．homework B．activity C．experiment D．language

A．except B．plus C．during D．including

A．help B．ask C．tell D．teach

A．already B．also C．afterwards D．almost

A．Although B．Because C．Unless D．And

A．fatter B．slimmer C．taller D．shorter

A．energy B．weight C．happiness D．experience

A．people’s B．person’s C．humans’ D．mankind’s

A．used to do B．are used to be C．used to be D．are used to being

A．should B．must C．may D．need

A．such as B．for example C．the same as D．so that

A．hands B．bones C．mouths D．feet