A、Four to five hours. B、Two to four hours. C、More than six hours. D、Only three hours. A

Today, I’d like to talk about how sitting for a long time will affect your health.
   Sitting is ubiquitous (普遍存在的) in our lives today. You know, we sit while we’re eating: we sit in the car, and we sit while we are watching TV. And many of us sit for many hours at work everyday. (16) So on average, Americans report that they sit between four and five hours a day. Exercise is important. But so is not sitting. You may exercise often, but that does not mean you can sit for the rest of your waking hours. We can’t throw away physical activity. It’s extremely important. The human body is designed to move. But modern lifestyles and office jobs rarely give us the chance to move around.
   In recent years, many researchers have assessed the relationship between sitting or television viewing and mortality. We have found that cutting television time to less than two hours a day could add 1.4 years to life.
   Now I will offer some suggestions for sitting less.
   First, new desk designs are helping. A "standing desk" lets people stand while they work. (17) Another new design is the "treadmill desk." It is an exercise machine that lets you walk in one place. Even some American schools are beginning to experiment with desks that are part bicycle to keep children moving.
   Second, do exercises while you are working. This is one of the strategies that many companies are using now. (18) Some companies have a bank of standing desks or treadmill desks where their employees can go for an hour a day and answer their emails or talk on the phone.
   Now, my final suggestion. If you work in office job or have a long-sitting job, you may have the following simple changes. (19) You may get up from your desk as often as you can, take walks at lunch time, and walk to your colleagues’ offices and talk directly to them instead of emailing them. All these activities may help you live longer.
16. How much time do Americans sit on average in a day?
17. What can we learn about the treadmill desk?
18. How could some companies deal with long sitting?
19. What should we do to live longer if we have a long-sitting job?