例題解析：
passage 1
Soot （煤灰） and Snow：a Hot Combination
New research from NASA scientists suggests emissions of black soot alter the way
sunlight reflects off snow．According to a computer simulation，black soot may be
responsible for 25 percent of observed global warming over the past century．
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．
Soot in areas with snow and ice may play an important role in climate change．Also，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．a(chǎn)s glaciers and ice sheets melt，they tend to get even dirtier,”said Dr．James Hansen，a researcher at NASA's Goddard Institute for Space Studies．New York．
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．
“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．
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 for the rest of this century．
The researchers found that observed warming in the Northern Hemisphere was large 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 1argest warming effects occurred when there were heavy snow cover and sufficient sunlight．
1．Paragraph 3 __.
2．Paragraph4 __.
3．Paragraph 6 __.
4．Paragraph 7 __.
5． In the twentieth century，soot __.
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 Effect 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 答案及解析：
1． 文章標(biāo)題分析：Soot （煤灰） and Snow：a Hot Combination
根據(jù)標(biāo)題內(nèi)容可以判斷該文章與自然環(huán)境（環(huán)境污染）有關(guān)。
2．被選項(xiàng)分析：
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
C Effect to Reduce Snow Albedo （反照率）
E Ways to Reduce Soot Emission
F Greenhouse Gases as the Main Factor of G1obal Warming
分析：被選項(xiàng)中都涉及到了文章標(biāo)題所揭示的核心詞，劃線(xiàn)結(jié)構(gòu)是小標(biāo)題中的核心結(jié)構(gòu)，也是可以用作答案線(xiàn)索的結(jié)構(gòu)。
直接解題：
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
C Effect to Reduce Snow Albedo （反照率）
E Ways to Reduce Soot Emission
F Greenhouse Gases as the Main Factor of G1obal Warming
1． Paragraph 3 __.
Soot in areas with snow and ice may play an important role in climate change．Also，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 sheets melt，they tend to get even dirtier,” said Dr．James Hansen，a researcher at NASA's Goddard Institute for Space Studies．New York．
1．C． 分析：段首句的大意和用詞似乎在暗示A是答案。但是在下文中沒(méi)有具體提到soot是如何改變氣候的（排除A）。段落中soot出現(xiàn)了兩次，因此重點(diǎn)注意包含soot的被選項(xiàng)： C和E。段落中沒(méi)有提到有關(guān)“煤灰散發(fā)”的問(wèn)題，所以排除E，選擇C。
提示：在借助段首句內(nèi)容的時(shí)候判斷答案的時(shí)候還應(yīng)該掃視一下全文。
A Soot’s Role in Changes in the Climate and the Atmosphere
B Observations of Warming in the Northern Hemisphere
C Effect to Reduce Snow Albedo （反照率）
E Ways to Reduce Soot Emission
F Greenhouse Gases as the Main Factor of G1obal Warming
2． Paragraph4 __
（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．
2．A．分析：因?yàn)槎温渲衧oot出現(xiàn)了兩次，因此重點(diǎn)注意包含soot的被選項(xiàng)： A和E，同樣段落中沒(méi)有提到有關(guān)“煤灰散發(fā)”的問(wèn)題，所以判斷A是答案（段落最后一句（觀點(diǎn)句）的含義與A一致）
提示：“避重就輕法”—段首句復(fù)雜則看段未句。
B Observations of Warming in the Northern Hemisphere
C Effect to Reduce Snow Albedo （反照率）
E Ways to Reduce Soot Emission
F Greenhouse Gases as the Main Factor of G1obal Warming
3． Paragraph 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 for the rest of this century．
3． F。 分析：因?yàn)槎温渲術(shù)as出現(xiàn)了兩次，因此重點(diǎn)注意包含gas的被選項(xiàng)：F。而F中的內(nèi)容正好與段首句中的核心結(jié)構(gòu)（it does not alter the fact that greenhouse gases are the primary cause of climate warming during the past century（它沒(méi)有改變‘溫室效應(yīng)是在過(guò)去的世紀(jì)中造成氣候變暖的主要原因’這個(gè)事實(shí)））一致。
B Observations of Warming in the Northern Hemisphere
C Effect to Reduce Snow Albedo （反照率）
E Ways to Reduce Soot Emission 4．Paragraph 7 __.
The researchers found that observed warming in the Northern Hemisphere was large 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 1argest warming effects occurred when there were heavy snow cover and sufficient sunlight．）
4． B．分析：段首句中出現(xiàn)了Northern Hemisphere，而接下來(lái)的句子中出現(xiàn)了“These observations”，這些詞都被包含在B中，因此判斷B是答案。
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
5. In the twentieth century, soot ___.
5. B。分析：結(jié)合文章標(biāo)題（主題）Soot （煤灰） and Snow：a Hot Combination，判斷B很可能是答案。也可以借助文章中的相關(guān)語(yǔ)句：According to a computer simulation，black soot may be responsible for 25 percent of observed global warming over the past century．
A produces much more global warming than a carbon-dioxide forcing of the same magnitude
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
6。Hansen cautioned that greenhouse gases__.
6．E． 分析：文章中提到溫室氣體仍然是造成全球溫度上升的主要因素，因此判斷E是答案。
A produces much more global warming than a carbon-dioxide forcing of the same magnitude
C can produce greenhouse gases
D absorb more of sun’s energy and warmth than white background
F can be seen mostly in the Northern Hemisphere
7． Black soot covered snow and ice__.
7． D。分析：該題可以借助常識(shí)直接判斷D是答案（帶有煤灰的冰和雪要比白色的背景吸收的熱量多）。
A produces much more global warming than a carbon-dioxide forcing of the same magnitude
C can produce greenhouse gases
F can be seen mostly in the Northern Hemisphere
8. A soot forcing is unusually effective，which__.
8． A。分析：借助提干中的核心詞soot forcing作為答案線(xiàn)索，這樣發(fā)現(xiàn)答案相關(guān)句：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（數(shù)量）.
passage 1
Soot （煤灰） and Snow：a Hot Combination
New research from NASA scientists suggests emissions of black soot alter the way
sunlight reflects off snow．According to a computer simulation，black soot may be
responsible for 25 percent of observed global warming over the past century．
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．
Soot in areas with snow and ice may play an important role in climate change．Also，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．a(chǎn)s glaciers and ice sheets melt，they tend to get even dirtier,”said Dr．James Hansen，a researcher at NASA's Goddard Institute for Space Studies．New York．
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．
“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．
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 for the rest of this century．
The researchers found that observed warming in the Northern Hemisphere was large 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 1argest warming effects occurred when there were heavy snow cover and sufficient sunlight．
1．Paragraph 3 __.
2．Paragraph4 __.
3．Paragraph 6 __.
4．Paragraph 7 __.
5． In the twentieth century，soot __.
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 Effect 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 答案及解析：
1． 文章標(biāo)題分析：Soot （煤灰） and Snow：a Hot Combination
根據(jù)標(biāo)題內(nèi)容可以判斷該文章與自然環(huán)境（環(huán)境污染）有關(guān)。
2．被選項(xiàng)分析：
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
C Effect to Reduce Snow Albedo （反照率）
E Ways to Reduce Soot Emission
F Greenhouse Gases as the Main Factor of G1obal Warming
分析：被選項(xiàng)中都涉及到了文章標(biāo)題所揭示的核心詞，劃線(xiàn)結(jié)構(gòu)是小標(biāo)題中的核心結(jié)構(gòu)，也是可以用作答案線(xiàn)索的結(jié)構(gòu)。
直接解題：
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
C Effect to Reduce Snow Albedo （反照率）
E Ways to Reduce Soot Emission
F Greenhouse Gases as the Main Factor of G1obal Warming
1． Paragraph 3 __.
Soot in areas with snow and ice may play an important role in climate change．Also，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 sheets melt，they tend to get even dirtier,” said Dr．James Hansen，a researcher at NASA's Goddard Institute for Space Studies．New York．
1．C． 分析：段首句的大意和用詞似乎在暗示A是答案。但是在下文中沒(méi)有具體提到soot是如何改變氣候的（排除A）。段落中soot出現(xiàn)了兩次，因此重點(diǎn)注意包含soot的被選項(xiàng)： C和E。段落中沒(méi)有提到有關(guān)“煤灰散發(fā)”的問(wèn)題，所以排除E，選擇C。
提示：在借助段首句內(nèi)容的時(shí)候判斷答案的時(shí)候還應(yīng)該掃視一下全文。
A Soot’s Role in Changes in the Climate and the Atmosphere
B Observations of Warming in the Northern Hemisphere
C Effect to Reduce Snow Albedo （反照率）
E Ways to Reduce Soot Emission
F Greenhouse Gases as the Main Factor of G1obal Warming
2． Paragraph4 __
（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．
2．A．分析：因?yàn)槎温渲衧oot出現(xiàn)了兩次，因此重點(diǎn)注意包含soot的被選項(xiàng)： A和E，同樣段落中沒(méi)有提到有關(guān)“煤灰散發(fā)”的問(wèn)題，所以判斷A是答案（段落最后一句（觀點(diǎn)句）的含義與A一致）
提示：“避重就輕法”—段首句復(fù)雜則看段未句。
B Observations of Warming in the Northern Hemisphere
C Effect to Reduce Snow Albedo （反照率）
E Ways to Reduce Soot Emission
F Greenhouse Gases as the Main Factor of G1obal Warming
3． Paragraph 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 for the rest of this century．
3． F。 分析：因?yàn)槎温渲術(shù)as出現(xiàn)了兩次，因此重點(diǎn)注意包含gas的被選項(xiàng)：F。而F中的內(nèi)容正好與段首句中的核心結(jié)構(gòu)（it does not alter the fact that greenhouse gases are the primary cause of climate warming during the past century（它沒(méi)有改變‘溫室效應(yīng)是在過(guò)去的世紀(jì)中造成氣候變暖的主要原因’這個(gè)事實(shí)））一致。
B Observations of Warming in the Northern Hemisphere
C Effect to Reduce Snow Albedo （反照率）
E Ways to Reduce Soot Emission 4．Paragraph 7 __.
The researchers found that observed warming in the Northern Hemisphere was large 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 1argest warming effects occurred when there were heavy snow cover and sufficient sunlight．）
4． B．分析：段首句中出現(xiàn)了Northern Hemisphere，而接下來(lái)的句子中出現(xiàn)了“These observations”，這些詞都被包含在B中，因此判斷B是答案。
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
5. In the twentieth century, soot ___.
5. B。分析：結(jié)合文章標(biāo)題（主題）Soot （煤灰） and Snow：a Hot Combination，判斷B很可能是答案。也可以借助文章中的相關(guān)語(yǔ)句：According to a computer simulation，black soot may be responsible for 25 percent of observed global warming over the past century．
A produces much more global warming than a carbon-dioxide forcing of the same magnitude
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
6。Hansen cautioned that greenhouse gases__.
6．E． 分析：文章中提到溫室氣體仍然是造成全球溫度上升的主要因素，因此判斷E是答案。
A produces much more global warming than a carbon-dioxide forcing of the same magnitude
C can produce greenhouse gases
D absorb more of sun’s energy and warmth than white background
F can be seen mostly in the Northern Hemisphere
7． Black soot covered snow and ice__.
7． D。分析：該題可以借助常識(shí)直接判斷D是答案（帶有煤灰的冰和雪要比白色的背景吸收的熱量多）。
A produces much more global warming than a carbon-dioxide forcing of the same magnitude
C can produce greenhouse gases
F can be seen mostly in the Northern Hemisphere
8. A soot forcing is unusually effective，which__.
8． A。分析：借助提干中的核心詞soot forcing作為答案線(xiàn)索，這樣發(fā)現(xiàn)答案相關(guān)句：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（數(shù)量）.