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The author is primarily concerned with ______.

A. condemning the U.S. for its failure to provide better medical care to the poor
B. evaluating the relative significance of factors contributing to the poor health status in the U. S.
C. providing information which the reader can use to improve his or her personal health
D. comparing the health status of the U.S. population with that of the world averages

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From the text we can learn that ______.

A. some managers are very young but already have their own business.
B. some managers are as casual and irresponsible as energetic young people.
C. the government is concerned about the lack of women in such a field as IT.
D. IT remains a minor area for growth.

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The author may most probably agree that ______.

A. it is a trend that businesses today go global
B. businesses today are very reluctant to go global
C. American businesses can make more money if they only sell home-made products
D. the market of the United States should not be that open

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Climate change is one of the most important environmental issues facing humankind. Understanding the potential impacts of climate change for natural ecosystems is essential if we are going to manage our environment to minimize the negative consequences of climate change and maximize the opportunities that it may offer. Because natural ecosystems are complex, nonlinear systems, it follows that their responses to climate change are likely to be complex. Climate change may affect natural ecosystems in a variety of ways. In the short term, climate change can alter the mix of plant species in land ecosystems such as grasslands. In the long term, climate change has the potential to dramatically alter the geographic distribution of major vegetation types--savannas, forests, and tundra. Climate change can also potentially alter global ecosystem processes, including the cycling of carbon, nitrogen, phosphorus, and sulfur. Moreover, changes in these ecosystem processes can affect and be affected by changes in the plant species of the ecosystem and vegetation type. All of the climate change-induced alterations of natural ecosystems affect the services that these ecosystems provide to humans.
The global average surface temperature increase of half a degree Celsius observed over the past century has been in part due to differential changes in daily maximum and minimum temperatures, resulting in a narrowing of the diurnal temperature range. Decreases in the diurnal temperature range were first identified in the United States, where large-area trends showed that maximum temperatures have remained constant or increased only slightly, whereas minimum temperature have increased at a faster rate. In this issue, Alward et al. report on the different sensitivities of rangeland plants to minimum temperatures increases.
Which of the following is NOT mentioned as a reason for the global warming？

A. The burning of fuels such as coal or oil.
B. The clearing of forests.
C. The cultivation of farmland.
D. The negative consequences of human activities.

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In subsequent paragraphs, we may expect the writer of this passage to ______.

A. discuss the global impacts of temperatures increases
B. present a point of view which supports the idea of the second paragraph
C. introduce Alward's report on the different sensitivities of rangeland plants to minimum temperatures increases
D. further illustrate the causes of the global average surface temperature increases

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