2. 考研
  3. Humans have altered the world’s climate by (1)_____ heat-trapping gases since almost the beginning of civilization and even prev

Humans have altered the world’s climate by (1)_____ heat-trapping gases since almost the beginning of civilization and even prev

admin2009-04-27  61
问题     Humans have altered the world’s climate by (1)_____ heat-trapping gases since almost the beginning of civilization and even prevented the start of an ice age several thousand years ago, a scientist said.
    Most scientists (2)_____ a rise (3)_____ global temperatures over the past century (4)_____ to emissions of carbon dioxide (5)_____ human activities like driving cars and operating factories.
    Dr. William Ruddiman, a professor at the University of Virginia, said at a meeting of the American Geophysical Union (6)_____ humans’ effect (7)_____ climate went back nearly 10, 000 years (8)_____ people gave up hunting and gathering and began farming.
    In a commentary accompanying the article, Dr. Thomas J. Crowley of Duke University, said he (9)_____ Dr. Ruddiman’s premise at first. "But when I started reading, Dr. Crowley wrote, "I could not help but (10)_____ whether he just might be (11)_____ something."
    The climate of the last 10,000 years has been unusually stable, (12)_____ civilization to flourish. But that is only because people chopped down swaths of forest in Europe, China and India for croplands and pastures. Carbon dioxide (13)_____ by the destruction of the forests, plus methane, another heat-trapping gas, (14)_____ by irrigated rice fields in Southeast Asia, trapped enough heat to (15)_____ an expected natural cooling.
    Levels of carbon dioxide and methane rise and fall in natural cycles (16)_____ thousands of years, and both reached a peak at the end of the last ice age 11;000 years ago. Both then declined (17)_____ expected.
    Both (18)_____ declining through the present day, leading to lower temperatures, and a new ice age should have begun 4,000 to 5,000 years ago, Dr. Ruddiman said. Instead, levels of carbon dioxide reversed 8,000 wears ago. The decline (19)_____ methane levels reversed 5,000 years ago, (20)_____ with the advent of irrigation rice farming.

选项 A、apply
B、attribute
C、attend
D、assign
答案B
解析 动词辨析。大多数科学家认为上个世纪的全球气温上升的部分原因是人类行为释放出的二氧化碳。本处需要一个动词与后面的协搭配。apply...to将…应用于，attend to注意，照顾，assign...to分配，attribute...to归因于，所以只有B是正确答案。
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