题目内容：

Your chair is your enemy. That is the conclusion of several recent studies. Among people who sit in front of the television for more than three hours each day, those who exercise are as fat as those who don’t.

         So what’s wrong with sitting? The answer seems to have two parts. The first is that sitting is one of the most passive things you can do. Compared to sitting, standing in one place is hard work. To stand, you have to tense your leg muscles, and engage the muscles of your back and shoulders; while standing, you often shift from leg to leg. All of this burns energy.

         You may think you have no choice about how much you sit. But this isn’t true. Suppose you sleep for eight hours each day, and exercise for one. That still leaves 15 hours of activities. Even if you exercise, most of the energy you burn will be burnt during these 15 hours, so weight gain is often the cumulative(累积的) effect of a series of small decisions: Do you take the stairs or the elevator? Do you walk to the corner store, or drive?

         But it looks as though there’s a more sinister aspect to sitting. Some evidence suggests that when you spend long periods sitting, your body actually does things that are bad for you.

         Lipoprotein lipase(蛋白脂酶) is a molecule that plays a central role in how the body processes fats. Low levels of lipoprotein lipase are associated with a variety of health problems. Studies in rats show that leg muscles only produce this molecule when they are actively being moved. The result is that when you sit, an important part of your metabolism(新陈代谢) slows down. You may also have a higher risk of suffering from diabetes(糖尿病).

        Some people have advanced radical solutions to the sitting syndrome(综合症): replace your sit-down desk with a stand-up desk, or watch television in a rocking chair. But whatever you choose, know this. The data is clear; look out for your chair.

1.What would be the best title of this passage?

         A．Become an Athlete to Be Healthy.

         B．Choose a Better Chair for You.

         C．How to Speed Up Your Metabolism.

         D．Stand Up While You Read This.

2.Paragraphs 2 and 3 tell us that          .

         A．taking too much exercise harms people’s health

         B．sitting a lot reduces the benefits of taking exercise

         C．people needn’t depend on exercise to keep healthy

         D．healthy people are those who sit less and stand more

3.Which of the following is the best advice on how to control our weight?

         A．Exercising at least an hour a day.

         B．Standing as long as possible.

         C．Using our energy actively in daily life.

         D．watching TV in a rocking chair.

4.The author mentions lipoprotein lipase mainly to           .

         A．show that it plays a big part in keeping us healthy

         B．tell us that it isn’t produced while we are sitting

         C．suggest that we should take less exercise to be healthy

         D．prove sitting for long is bad for our body