2. 外语
  3. Scientific consensus is that humans first began to have a warming effect on Earth’s climate within the past century, after coal-

Scientific consensus is that humans first began to have a warming effect on Earth’s climate within the past century, after coal-

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问题     Scientific consensus is that humans first began to have a warming effect on Earth’s climate within the past century, after coal-burning factories, power plants, and motor vehicles began releasing carbon dioxide (CO2) and other greenhouse gases in significant quantities into the air. However, evidence suggests that human agricultural activities may have had such an effect much earlier: concentrations of CO2 started rising about 8000 years ago, even though natural trends indicate they should have been dropping; methane levels rose similarly about 3,000 years later. Without these rises, however, current temperatures in northern parts of North America and Europe would be cooler by three to four degrees Celsius—enough to inhibit agriculture—and an ice age would probably have begun several thousand years ago in northeastern Canada.
Which of the following best describes the function of the highlighted sentence?
选项 A、It undermines the assumption that human activity has had a significant impact on Earth’s climate
B、It supports the assumption that Earth’s temperatures have risen appreciably over the past 100 years
C、It questions the assumption that greenhouse gases have had a warming effect on Earth’s climate
D、It challenges the assumption that human activity began to affect Earth’s climate after the advent of industrialization
E、It supports the assumption that greenhouse gases are a direct by-product of industrial activities
答案D
解析 本题属于功能题，正确答案是定位句3s版本，即人类的农业活动在更早之前已经导致全球变暖了，因此选项D正确。A项新老观点都认为人类活动对全球气候产生了影响，只是区别在于何时产生了影响。B项是“反驳”而非“支持”，因为标黑体句子与前一句取反。C项新老观点都认为温室气体对全球气候有变暖的影响。E项是“反驳”而非“支持”，因为标黑体句子与前一句取反。
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