题目内容：

    There is virtue in working standing up. It sounds like a fashion. But it does have a basis in science.

That, by itself, may not be surprising. Health ministries ask people for decades to do more exercise. What is surprising is that long periods of inactivity are bad regardless of how much time you also spend on officially approved high-impact stuff like pounding treadmills(跑步机) in the gym. What you need instead, the latest research suggests, is constant low-level activity. This can be so low-level that you might not think of it as activity at all. Even just standing up counts, for it invokes muscles that sitting does not.

Researchers in this field trace the history of the idea that standing up is good for you back to 1953, when a study published in The Lancet found that bus conductors, who spent their days standing, had a risk of heart attack half that of bus drivers, who spent their shifts on their backsides. But as the health benefits of exercise and vigorous(强度大的) physical activity began to become clear in the 1970s, says David Dunstan, a researcher at the Baker IDI Heart & Diabetes Institute in Melbourne, Australia, interest in low-intensity activity --- like walking and standing --- became weaker.

Over the past few years, however, interest has been excited again. A series of studies, none big enough to provide convincing evidence, but all pointing in the same direction, persuaded Emma Wilmot of the University of Leicester, in Britain, to carry out a meta-analysis. This is a technique that combines diverse studies in a statistically meaningful way. Dr Wilmot combined 18 of them, covering almost 800,000 people and concluded that those individuals who are the least active in their normal daily lives are twice as likely to develop diabetes(糖尿病) as those who are the most active. She also found that the immobile are twice as likely to die from a heart attack and two-and-a-half times as likely to suffer cardiovascular disease as the most mobile. Crucially, all this seemed to be independent of the amount of vigorous, gym-style exercise that volunteers did.

1.The surprising thing mentioned in Paragraph 2 is that ______.

A. Low-level activities are better than high-level ones.

B. Long periods of inactivity are bad to people’s health

C. The benefits of high-impact exercise are not highly approved by people

D. Strong physical activities cannot make up for the bad effects of inactivity.

2.Why did people lose interest in low-intensity activity in the 1970s?

A. Researchers didn’t devote much to studying their health benefits.

B. The health benefits of high-impact exercise were widely recognized.

C. It was believed to be unable to invoke all the muscles of the body.

D. It was proved not so effective in reducing the risk of heart attacks.

3.The findings made by Dr Wilmot ______.

A. disagreed with her assumption

B. consisted with the results of the 1953 study

C. changed her original research objectives

D. confirmed David Dunstan’s research results

4.What’s the passage mainly about?

A. The history of the theory.

B. The benefits of standing up.

C. Low-level activity and health.

D. A series of epidemiological studies.