2 Soot in the higher latitudes of the Earth.where ice is more common，absorbs more of the sun's energy and warmth than an icy， white background.Dark-colored black carbon，or soot，absorbs sunlight，while lighter colored ice reflects sunlight.
3 Soot in areas with snow and ice may play all important role in climate change.Als0，if snow and ice covered areas begin melting.the warming effect increases，as the soot becomes more concentrated on the snow surface.“This provides a positive feedback，as glaciers and ice sheet smelt，they tend to get even dirtier，” said Dr.James Hansen，a researcher at NASA's Goddard Institute for Space Studies，NewYork.
4 Hansen found soot's effect on snow albedo（solar energy reflected back to space），which may be contributing to trends toward early springs in the Northern Hemisphere，such as thinning Arctic sea ice，melting glaciers and permafrost.Soot also is believed to play a role in changes in the atmosphere above the oceans and land.
5 “Black carbon reduces the amount of energy reflected by snow back into space，thus heating the snow surface more than if there were no black carbon~，”Hansen said.Soot's increased absorption of solar energy is especially effective in warming the world's climate. “This forcing is unusually effective，causing twice as much global warming as a carbon.dioxide forcing of the same magnitude，”Hansen noted.
6 Hansen cautioned.although the role of soot in altering global climate is substantial，it does not alter the fact that greenhouse gases are the primary cause of climate warming during the past century.Such gases are expected to be the largest climate forcing f10r也e rest of this century.
7 The researchers found that observed warming in the Northern Hemisphere was 1arge in the winter and spring at middle and high latitudes.These observations were consistent with the researchers' climate model simulations，which showed some of the largest warming effects occurred when there were heavy snow cover and sufficient sunlight.
词汇：
soot n.煤烟，煤灰
emission n.释放，散发，排放
simulation v.模拟
latitude n.纬度
glacier n.冰川，冰河
albedo n.反照率
permafrost n.永冻层
forcing n.温室作用
dioxide n.二氧化物
magnitude n.量，大小
练习：
1.Paragraph 3____________
2.Paragraph 4____________
3.Paragraph 6____________
4.Paragraph 7____________
A Soot's Role in Changes in the Climate and the Atmosphere
B Observations of Warming in the Northern Hemisphere
C Explanation of Increased Warming Effect Caused by Soot
D Effort to Reduce Snow Albedo
E Ways to Reduce Soot Emission
F Greenhouse Gases as the Main Factor of G10bal Warming
5.In the twentieth century，soot____________
6.Hansen cautioned that greenhouse gases____________
7. Black soot covered snow and ice____________
8.A soot forcing is unusually effective，which____________
A produces much more global warming than a carbon？dioxide forcing of the same magnitude
B contributed to 25 percent of observed global warming
C can produce greenhouse gases
D absorb more of sun's energy and warmth than white background
E still surpass soot in warming the world's climate during the last century
F can be seen mostly in the Northern Hemisphere
第四部分：阅读理解（每题3分，共45分）
下面有3篇短文，每篇短文后有5道题，每道题后面有4个选项。请仔细阅读短文并根据短文回答其后面的问题，从4个选项中选择1个最佳答案涂在答题卡相应的位置上。
第1篇
Goal of American Education
Education is all enormous and expensive part of American life. Its size is matched by its variety.
Differences in American schools compared with those found in the majority of other
countries lie in the fact that education here has long been intended for everyone—not just
for a privileged elite. Schools ale expected to meet the needs of every child， regardless
of ability， and also the needs of society itself.This means that public schools offer more
than academic subjects.It surprises many people when t11ey come here to find high schools
offering such courses as typing，sewing，radio repair， computer programming or driver training，along with traditional academic subjects such as mathematics，history， and languages.Students choose their curricula depending on their interests，future goals，and level of ability.The underlying goal of American education is to develop every child to the utmost of his or her own possibilities，and to give each one a sense of civic and community consciousness.。
Schools have traditionally played an important role in creating national unity and
“Americanizing”the millions of immigrants who have poured into this country from many
different backgrounds and origins. Schools still play a large role in the community， especially in the small towns.
The approach to teaching may seem unfamiliar to many， not only because it is informal，
but also because there is not much emphasis on learning facts.Instead，Americans try to
teach their children toⅡ1ink for themselves and to develop their own intellectual and
creative abilities.Students spend much time，learning how to use resource materials libraries， statistics and computers.Americans believe that if children are taught to reason well and to research well， they will be able to find whatever facts they need throughout the rest of their lives.Knowing how to solve problems is considered more important than the accumulation of facts.
This is America's answer to the searching question that thoughtful parents all over the world are asking themselves in the fast-moving time：“How Can one prepare today's child for a tomorrow that one can neither predict nor understand？”
词汇：
privileged adj.享有特权的
elite n.精英，精华
curricula n.课程
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