西南财经大学
Blood vessels running all through the lungs carry blood to each air sac(囊), or alveolus(肺泡), and then back again to the heart. Only the thin wall of the air sac and the thin wall of a capillary(毛细血管)are between the air and the blood. So oxygen easily diffuses from the air sacs through the walls into the blood, while carbon dioxide easily diffuses from the blood through the walls into the air sacs.When blood is sent to the lungs by the heart, it has come back from the cells in the rest of the body. So the blood that goes into the wall of an air sac contains much dissolved carbon dioxide but very little oxygen. At the same time, the air that goes into the air sac contains much oxygen but very little carbon dioxide. You have learned that dissolved materials always diffuse from where there is more of them to where there is less. Oxygen from the air dissolves in the moisture on the lining of the air sac and diffuses through the lining into the blood. Meanwhile, carbon dioxide diffuses from the blood into the air sac. The blood then flows from the lungs back to the heart, which sends it out to all other parts of the body.Soon after air goes into an air sac, it gives up some of its oxygen and takes in some carbon dioxide from the blood. To keep diffusion going as it should, this carbon dioxide must be gotten rid of. Breathing, which is caused by movements of the chest, forces the used air out of the air sacs in your lungs and brings in fresh air. The breathing muscles are controlled automatically so that you breathe at the proper rote to keep your air sacs supplied with fresh air. Ordinarily, you breathe about twenty-two times a minute. Of course, you breathe faster when you are exercising and slower when you are resting. Fresh air is brought into your lungs when you breathe in, or inhale(吸入), while used air is forced out of your lungs when you breathe out, or exhale.Some people think that all the oxygen is taken out of the air in the lungs and that what we breathe out is pure carbon dioxide. But these ideas are not correct. Air is a mixture of gases that is mostly nitrogen(氮). This gas is not used in the body. So the amount of nitrogen does not change as air is breathed in and out. But while air is in the lungs, it is changed in three ways: (1) About one fifth of the oxygen in the air goes into the blood. (2) An almost equal amount of carbon dioxide comes out of the blood into the air. (3) Moisture from the linings of the air passages and air sacs evaporates until the air is almost saturated.1.It can be inferred from the passage that oxygen and carbon dioxide(  ).2.When blood travels back to the lungs by the heart, (  ).  3.The movement of breathing can effectively (  ).  4.When we breathe out, the amount of nitrogen (  ).  5.The air in the lungs changes through(  ).
Global warming is causing more than 300,000 deaths and about $125 billion in economic losses each year, according to a report by the Global Humanitarian Forum, an organization led by Kofi Annan, the former United Nations secretary general.The report, to be released Friday analyzed data and existing studies of health, disaster, population and economics trends. It found that human-influenced climate changes was raising the global death rates from illnesses including malnutrition(营养不良)and heat-related health problems.But even before its release, the report drew criticism from some experts on climate and risk, who questioned its methods and conclusions.Along with the deaths, the report said that the lives of 325 million people, primarily in poor countries, were being seriously affected by climate change. It projected that the number would double by 2030.Roger Pielke Jr., a political scientist at the University of Colorado, Boulder, who studies disaster trends, said the Forum’s report was “a methodological embarrassment” because there was no way to distinguish deaths or economic losses related to human driven global warming amid the much larger losses resulting from the growth in populations and economic development in vulnerable regions. Dr. Pielke said that “climate change is an important problem requiring our utmost attention”. But the report, he said, “will harm the cause for action on both climate change and disasters because it is so deeply flawed(有瑕疵的)”.However, Soren Anderasen, a social scientist at Dahl berg Global Development Partners who supervised the writing of the report, defended it, saying that it was clear that the numbers were rough estimates. He said the report was aimed at world leaders, who will meet in Copenhagen in December to negotiate a new international climate treaty.In a press release describing the report, Mr. Annan stressed the need for the negotiations to focus on increasing the flow of money from rich to poor regions to help reduce their vulnerability to climate hazards, while still curbing the emissions of the heat trapping gases. More than 90% of the human and economic losses from climate change are occurring in poor countries, according to the report.1.What is the finding of the Global Humanitarian Forum?2.What do we learn about the Forum’s report from the passage?3.What does Dr. Pielke say about the Forum’s report?4.What is Soren Andreasen’s view of the report?5.What does Kofi Annan say should be the focus of the Copenhagen conference?
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