阅读理解。 Living in a green area can make you live longer, according to research published today. The research also shows that the difference in life expectancy (预期寿命) between rich and poor becomes smaller among those who live in an environment with parks and trees. Richard Mitchell, from Glasgow University, and his colleagues, found that the gap between the number of deaths of people on high incomes and the number of deaths of those on low incomes in green areas was half that compared with figures relatingto built-up areas. Green spaces, classified by the researchers as "open, undeveloped land with natural vegetation", encouraged people to walk and be more active. Exercise in these settings could have greater benefits than exercise elsewhere, the researchers said. The benefits potentially go beyond exercise. Studies have shown that being around green spaces can reduce blood pressure and stress levels, and possibly help patients recover faster. A number of researchers have looked at the effects of greenery on our well-being.But few studies had looked at whether living in green areas reduced health inequalities,the Glasgow team said. Using information from a land-use database of 2001, the researchers divided the pre-retirement population of England into four groups according to income level, and five groups according to access to green space. They then looked at death rate for 2001～2005. They found that the inequality in death rate from all causes relating to lack of money was less in those populations in the greenest areas compared with the figuresfor people living in more built-up places. They found an even stronger relationship when it came to deaths from certain diseases such as heart conditions and stroke (中风). There was no difference, however, in deaths from lung cancer. The researchers said that changing the physical environment was an easier way to fightagainst poor health than using media campaigns or giving out information on health. "The result of the study is clear: Environments that promote good health might be very importantin the fight to reduce health inequalities." 1. The underlined word "that" in Paragraph 2 refers to _____. [ ] A. the gapB. the number of deaths C. the income D. the living area 2. What was the special point of the Glasgow team's research? [ ] A. They offered a scientific definition of "green spaces". B. They encouraged people to exercise in green areas. C. They studied the effects of greenery on people's health. D. They focused on the influence of greenery on health inequalities. 3. What advice would the researchers probably give according to the last paragraph? [ ] A. More health information should be given to the public. B. People should take more exercise every day. C. More trees and grass should be planted in cities. D. People should help to fight against health problems. 4. What is the main idea of the passage? [ ] A. People should live in green areas. B. Green spaces promote good health. C. Income influences health less than environment. D. Exercise in green areas benefits people a lot.