[单项选择]

Arctic Melt

Earth’s North and South Poles are famous for being cold and icy. Last year, however, the amount of ice in the Arctic Ocean fell to a record low.
Normally, ice builds in Arctic waters around the North Pole each winter and shrinks during the summer. But for many years, the amount of ice left by the end of summer has been declining.
Since 1979, each decade has seen an 11.4 percent drop in end of summer ice cover. Between 1981 and 2000, ice in the Arctic lost 22 percent of its thickness, becoming 1.13 meters thinner.
Last summer, Arctic sea ice reached its skimpiest levels yet. By the end of summer 2007, the ice had shrunk to cover just 4.2 million square kilometers. That’s 38 percent less area than the average cover at that time of year. And it’s a very large 23 percent below the previous record low, which was set just 2 years ago. This continuing trend has scientists concern
A. construct
B. extend
C. create
D. expand

[单项选择]

Earth’s North and South Poles are famous for being cold and icy. Last year, however, the amount of ice in the Arctic Ocean fell to a record low.
Normally, ice builds in Arctic waters around the North Pole each winter and shrinks during the summer. But for many years, the amount of ice left by the end of summer has been declining.
Since 1979, each decade has seen an 11.4 percent drop in end of summer ice cover. Between 1981 and 2000, ice in the Arctic lost 22 percent of its thickness, becoming 1.13 meters thinner.
Last summer, Arctic sea ice reached its skimpiest levels yet. By the end of summer 2007, the ice had shrunk to cover just 4.2 million square kilometers. That’s 38 percent less area than the average cover at that time of year. And it’s a very large 23 percent below the previous record low, which was set just 2 years ago. This continuing trend has scientists concern
A. 4.2 million square kilometers
B. 11.4 million square kilometers
C. 1.13 million square kilometers
D. 38 million square kilometers

[单项选择]
Earth’s North and South Poles are famous for being cold and icy. Last year, however, the amount of ice in the Arctic Ocean fell to a record low.
Normally, ice builds in Arctic waters around the North Pole each winter and shrinks during the summer. But for many years, the amount of ice left by the end of summer has been declining.
Since 1979, each decade has seen an 11.4 percent drop in end of summer ice cover. Between 1981 and 2000, ice in the Arctic lost 22 percent of its thickness, becoming 1.13 meters thinner.
Last summer, Arctic sea ice reached its skimpiest levels yet. By the end of summer 2007, the ice had shrunk to cover just 4.2 million square kilometers. That’s 38 percent less area than the average cover at that time of year. And it’s a very large 23 percent below the previous record low, which was set just 2 years ago. This continuing trend has scientists concerned.
There may be several reasons fo
A. construct
B. extend
C. create
D. expand

[单项选择]
Earth’s North and South Poles are famous for being cold and icy．Last year，however，the amount of ice in the Arctic Ocean(北冰洋)fell to a record low．
Normally，ice builds in Arctic waters around the North Pole each winter and shrinks(缩小)during the summer．But for many years，the amount of ice left by the end of summer has been declining．
Since 1979，each decade has seen an 11.4 percent drop in end-of-summer ice cover．Between 1981 and 2000．ice in the Arctic lost 22 percent of its thickness-becoming 1.13 meters thinner．
Last summer，Arctic sea ice reached its thinnest levels yet．By the end of summer 2007，the ice had shrunk to cover just 4.2 million square kilometers．That’s 38 percent less area than the average cover at that time of year．And it’s a very large 23 percent below the previous record low，which was set just 2 years ago．This continuing trend has made scientists concerned．
There may be several reasons for
A. establishes．
B. expands．
C. creates．
D. constructs．