Maybe you should sit down before you read this． It's a little frightening． Your sitting may be killing you．

Health experts say the U．S． adult now sits about 6.5 hours a day. That is up about an hour a day compared to 2007． The news is even worse for teens． They sit eight hours each day．The information was put out by the National Center for Health Statistics．It has collected the numbers for the past 16 years．It is worried about what it has found．

Research shows that people who are not active can get sick． Their bones get weaker． They burn fewer calories （卡路里）． That makes them more likely to put on too much weight． They might even get diabetes （糖尿病）． They are at risk for high blood pressure and heart problems， too．

Some experts also think sitting too much can influence how your blood moves through your body and how well your body fights off illness． Being active helps in lots of ways． It can make you happier， burn more calories and give you more energy． It can also help you sleep better．

About 60% of people in the U．S． watch at least two hours of TV each day． That number has stayed about the same in recent years．

Computers are the biggest reason for more hours spent sitting． Computer use outside of work or school has gone up for all age groups． Now， 50% of adults spend at least an hour of their free time on a computer each day． That is up from 29% in 2003．

About 53% of teens now spend at least an hour of free time on computers． So do 56% of kids． As many as 1 in 4 people who use computers use one for three hours or more outside of work and school．

So get up， take some breaks and go outside． You might save your life by doing outdoor

activities．

（1）The text is especially helpful for those who care about 　　．

A．	their body shape
B．	their home comforts
C．	their health
D．	their food

（2）Being active can help people 　　．

A．	burn more calories
B．	forget their pressure
C．	get sick
D．	treat heart problems

（3）What is the text mainly about？ 　　

A．	Computers are causing health problems．
B．	Too much sitting is influencing our health．
C．	Being more active is good for you and me．
D．	Sitting means killing．

（4）Which one of the following is most probably to be discussed next？ 　　

A．	The cause of diabetes．
B．	Introduce some outdoor activities．
C．	Give some examples of losing weight successfully
D．	List some disadvantages of playing computer games．