单选题Snow _____ is a big problem in some areas after the snow storm which lasts several days.A mobilizationB promotionC motiveD removal

Many people believe the glare from snow causes snow-blindness． Yet, dark glasses or not,they find themselves suffering from headaches and watering eyes, and even snow-blindness, when exposed to several hours of "snow light"．
The United States Army has now determined that glare from snow does not cause snow-
blindness in troops in a snow-covered country． Rather, a man's eyes frequently find nothing to focus on in a broad expanse of barren snow-covered terrain． So his gaze continually shifts and jumps back and forth over the entire landscape in search of something to look at． Finding nothing,hour after hour, the eyes never stop searching and the eyeballs become sore and the eye musclesache． Nature offsets this irritation by producing more and fluid which covers the eyeball． The fluid covers the eyeball in increasing quantity until vision blurs, then is observed, and the result is
total, even though temporary, snow-blindness．
Experiments led the Army to a simple method of overcoming this problem． Scouts ahead of a main body of troops are trained to shake snow from evergreen bushes, creating a dotted line as they cross completely snow-covered landscape． Even the scouts themselves throw lightweight, dark colored objects ahead on which they too can focus． The men following can then see something．Their gaze is arrested． Their eyes focus on a bush and having found something to see, stop scouring the snow-blanketed landscape． By focusing their attention on one object at a time, the men can cross the snow without becoming hopelessly snow-blind or lost． In this way the problem of crossing a solid white terrain is overcome．
Snow-blindness may be avoided by__________

A.concentrating to the solid white terrain
B.searching for something to look at in snow-covered terrain
C.providing the eyes with something to focus on
D.covering the eyeballs with fluid

Many people believe the glare from snow causes snow-blindness． Yet, dark glasses or not,they find themselves suffering from headaches and watering eyes, and even snow-blindness, when exposed to several hours of "snow light"．
The United States Army has now determined that glare from snow does not cause snow-
blindness in troops in a snow-covered country． Rather, a man's eyes frequently find nothing to focus on in a broad expanse of barren snow-covered terrain． So his gaze continually shifts and jumps back and forth over the entire landscape in search of something to look at． Finding nothing,hour after hour, the eyes never stop searching and the eyeballs become sore and the eye musclesache． Nature offsets this irritation by producing more and fluid which covers the eyeball． The fluid covers the eyeball in increasing quantity until vision blurs, then is observed, and the result is
total, even though temporary, snow-blindness．
Experiments led the Army to a simple method of overcoming this problem． Scouts ahead of a main body of troops are trained to shake snow from evergreen bushes, creating a dotted line as they cross completely snow-covered landscape． Even the scouts themselves throw lightweight, dark colored objects ahead on which they too can focus． The men following can then see something．Their gaze is arrested． Their eyes focus on a bush and having found something to see, stop scouring the snow-blanketed landscape． By focusing their attention on one object at a time, the men can cross the snow without becoming hopelessly snow-blind or lost． In this way the problem of crossing a solid white terrain is overcome．
A suitable title for this passage would be __________ ．

A.Snow-Blindness and How to Overcome It
B.Nature's Cure for Snow Blindness
C.Soldiers in the Snow
D.Snow Vision

共用题干
New research from NASA scientists suggests emissions of black soot after the way sunlight re- flects 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（维度）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 increase,as the soot becomes more con-centrated 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.
Hansen found soot's effect on snow albedo（反照率）,which may be contributing to trends to-ward early springs in the Northern Hemisphere,such as thinning Arctic sea ice and melting glac-iers 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 absorp-tion of solar energy is especially effective in warming the world's climate.“ This forcing is unusual-ly effective,causing twice as much global warming as a carbon-dioxide forcing of the same magni-tude.”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 the 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 coherent with the researchers' climate model situations,which showed some of the largest warming effects occurred when there were heavy snow cover and sufficient sunlight.

What is the main cause of climate warming during the past century?
A: Soot.
B: Snow.
C: Greenhouse gases.
D:.Wind.

共用题干
New research from NASA scientists suggests emissions of black soot after the way sunlight re- flects 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（维度）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 increase,as the soot becomes more con-centrated 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.
Hansen found soot's effect on snow albedo（反照率）,which may be contributing to trends to-ward early springs in the Northern Hemisphere,such as thinning Arctic sea ice and melting glac-iers 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 absorp-tion of solar energy is especially effective in warming the world's climate.“ This forcing is unusual-ly effective,causing twice as much global warming as a carbon-dioxide forcing of the same magni-tude.”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 the 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 coherent with the researchers' climate model situations,which showed some of the largest warming effects occurred when there were heavy snow cover and sufficient sunlight.

Which of the following statements of soot is NOT true?
A: It absorbs sun's heat.
B: It is responsible for climate change.
C: It reflects sunlight.
D:.It may account for a quarter of global warming over the past century.

__________

A.town
B.how
C.down
D.snow

Many people believe the glare from snow causes snow-blindness． Yet, dark glasses or not,they find themselves suffering from headaches and watering eyes, and even snow-blindness, when exposed to several hours of "snow light"．
The United States Army has now determined that glare from snow does not cause snow-
blindness in troops in a snow-covered country． Rather, a man's eyes frequently find nothing to focus on in a broad expanse of barren snow-covered terrain． So his gaze continually shifts and jumps back and forth over the entire landscape in search of something to look at． Finding nothing,hour after hour, the eyes never stop searching and the eyeballs become sore and the eye musclesache． Nature offsets this irritation by producing more and fluid which covers the eyeball． The fluid covers the eyeball in increasing quantity until vision blurs, then is observed, and the result is
total, even though temporary, snow-blindness．
Experiments led the Army to a simple method of overcoming this problem． Scouts ahead of a main body of troops are trained to shake snow from evergreen bushes, creating a dotted line as they cross completely snow-covered landscape． Even the scouts themselves throw lightweight, dark colored objects ahead on which they too can focus． The men following can then see something．Their gaze is arrested． Their eyes focus on a bush and having found something to see, stop scouring the snow-blanketed landscape． By focusing their attention on one object at a time, the men can cross the snow without becoming hopelessly snow-blind or lost． In this way the problem of crossing a solid white terrain is overcome．
?The scouts shake snow from evergreen bushes in order to__________ ．

A.give the men behind something to see
B.beautify the landscape
C.warm themselves in the cold
D.prevent the men behind from losing their way

Many people believe the glare from snow causes snow-blindness． Yet, dark glasses or not,they find themselves suffering from headaches and watering eyes, and even snow-blindness, when exposed to several hours of "snow light"．
The United States Army has now determined that glare from snow does not cause snow-
blindness in troops in a snow-covered country． Rather, a man's eyes frequently find nothing to focus on in a broad expanse of barren snow-covered terrain． So his gaze continually shifts and jumps back and forth over the entire landscape in search of something to look at． Finding nothing,hour after hour, the eyes never stop searching and the eyeballs become sore and the eye musclesache． Nature offsets this irritation by producing more and fluid which covers the eyeball． The fluid covers the eyeball in increasing quantity until vision blurs, then is observed, and the result is
total, even though temporary, snow-blindness．
Experiments led the Army to a simple method of overcoming this problem． Scouts ahead of a main body of troops are trained to shake snow from evergreen bushes, creating a dotted line as they cross completely snow-covered landscape． Even the scouts themselves throw lightweight, dark colored objects ahead on which they too can focus． The men following can then see something．Their gaze is arrested． Their eyes focus on a bush and having found something to see, stop scouring the snow-blanketed landscape． By focusing their attention on one object at a time, the men can cross the snow without becoming hopelessly snow-blind or lost． In this way the problem of crossing a solid white terrain is overcome．
To prevent headaches, watering eyes and blindness caused by the glare from snow, dark glasses are__________ ．

A.indispensible
B.useful
C.ineffective
D.available

A ski trail is densely packed with snow.

A:inexpensively
B:quickly
C:carefully
D:thickly

共用题干
New research from NASA scientists suggests emissions of black soot after the way sunlight re- flects 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（维度）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 increase,as the soot becomes more con-centrated 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.
Hansen found soot's effect on snow albedo（反照率）,which may be contributing to trends to-ward early springs in the Northern Hemisphere,such as thinning Arctic sea ice and melting glac-iers 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 absorp-tion of solar energy is especially effective in warming the world's climate.“ This forcing is unusual-ly effective,causing twice as much global warming as a carbon-dioxide forcing of the same magni-tude.”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 the 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 coherent with the researchers' climate model situations,which showed some of the largest warming effects occurred when there were heavy snow cover and sufficient sunlight.

“This forcing” in Paragraph 5 refers to_____.
A: sun's heating on snow surface
B: soot's increased absorption of solar energy
C: carbon-dioxide's warming effect
D: snow's increased reflection of sunlight

共用题干
New research from NASA scientists suggests emissions of black soot after the way sunlight re- flects 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（维度）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 increase,as the soot becomes more con-centrated 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.
Hansen found soot's effect on snow albedo（反照率）,which may be contributing to trends to-ward early springs in the Northern Hemisphere,such as thinning Arctic sea ice and melting glac-iers 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 absorp-tion of solar energy is especially effective in warming the world's climate.“ This forcing is unusual-ly effective,causing twice as much global warming as a carbon-dioxide forcing of the same magni-tude.”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 the 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 coherent with the researchers' climate model situations,which showed some of the largest warming effects occurred when there were heavy snow cover and sufficient sunlight.

Which of the following areas shows a greater warming effect?
A: Ice sea areas.
B: Areas with black carbon.
C: Areas covered with white snow.
D: Melting glaciers.