[单项选择]When scientists first warned in the 1970s that CFCs could attack ozone, the U.S. responded by banning their use in spray cans. But the rest of the world continued to use CFC - based aerosol cans , and overall CFC production kept growing. The threat became far clearer in 1985 , when researchers reported a "hole" in the ozone layer over Antarctic. Although the size of the hole varies with the seasons and weather patterns, at times Antarctic ozone has been depleted by as much as 50% in some spots. As a result of this disturbing development, 24 nations, including the U. S. and the Soviet Union, met in Montreal two summers ago and agreed to cut back on CFCs. The so - called Montreal Protocal is designed to achieve a 35% net reduction in worldwide CFC production by 1999.
That’s not good enough, however, the same stability that makes CFC so safe in industrial use makes them extremely longlives, some of the CFCs released today will still be in the atmosphere a century from now. Moreover,
A. that CFC manufacture is completely forbidden
B. that the production of CFC is reduced
C. to find substitutes for CFCs
D. to reduce the danger of CFCs

[单项选择]When scientists first warned in the 1970s that CFCs could attack ozone, the U.S. responded by banning their use in spray cans. But the rest of the world continued to use CFC - based aerosol cans , and overall CFC production kept growing. The threat became far clearer in 1985 , when researchers reported a "hole" in the ozone layer over Antarctic. Although the size of the hole varies with the seasons and weather patterns, at times Antarctic ozone has been depleted by as much as 50% in some spots. As a result of this disturbing development, 24 nations, including the U. S. and the Soviet Union, met in Montreal two summers ago and agreed to cut back on CFCs. The so - called Montreal Protocal is designed to achieve a 35% net reduction in worldwide CFC production by 1999.
That’s not good enough, however, the same stability that makes CFC so safe in industrial use makes them extremely longlives, some of the CFCs released today will still be in the atmosphere a century from now. Moreover,
A. Because the CFCs directly damage the people’s health.
B. Because the CFCs are poisonous chemicals.
C. Because the production of the CFCs costs a lot.
D. Because the CFCs can attack ozone by liberating atoms of chlorine.

[单项选择]
When scientists first warned in the 1970s that CFCs could attack ozone, the U.S. responded by banning their use in spray cans. But the rest of the world continued to use CFC -based aerosol cans, and overall CFC production kept growing. The threat became far clearer in 1985, when researchers reported a "hole" in the ozone layer over Antarctic. Although the size of the bole varies with the seasons and weather patterns, at times Antarctic ozone has been depleted by as much as 50% in some spots. As a result of this disturbing de- velopment,24 nations, including the U. S. and the Soviet Union, met in Montreal two summers ago and a- greed to cut back on CFCs. The so - called Montreal Protocal is designed to achieve a 35% net reduction in worldwide CFC production by 1999.
That’s not good enough, however, the same stability that makes CFC so safe in industrial use makes them extremely longlives, some of the CFCs rele
A. Because the CFCs directly damage the people’s health.
B. Because the CFCs are poisonous chemicals.
C. Because the production of the CFCs costs a lot.
D. Because the CFCs can attack ozone by liberating atoms of chlorine.

[单项选择]

Scientists have long warned that some level of global warming is a done deal—due in large part to heat-trapping greenhouse gases humans already have pumped skyward. Now, however, researchers are fleshing out how much future warming and sea-level rise the world has triggered. The implicit message: "We can’t stop this, so how do we live with it" says Thomas Wigley, a climate researcher at NCAR.
One group, led by Gerald Meehl at NCAR, used two state-of-the-art climate models to explore what could happen if the world had held atmospheric concentrations of greenhouse gases steady since 2000. The results: Even if the world had slammed on the brakes five years ago, global average temperatures would rise by about 1 degree Fahrenheit by the end of the 21st century. Sea levels would rise by another 4 inches over 20th-century increases. Rising sea-levels would continue well beyond 2100, even without adding water from melting glaciers and ice sheets. The rise hi
A. getting worse because of a culture bias.
B. caused by the rise of the sea level.
C. people have to live with.
D. we don’t need to worry about in the future.